1. Structure of the Encyclopedia EOLSS-bullet

The EOLSS body of knowledge is an integrated compendium of twenty one component encyclopedias (also known as Subject Categories) .It is the world’s largest source of thematically organized knowledge. It has been developed under the auspices of UNESCO and published by Eolss Publishers, Oxford, UK. The EOLSS attempts to forge pathways between disciplines in order to show their interdependence and help foster the transdisciplinary aspects of the relationship between nature and human society (the anthroposphere).It deals in detail with interdisciplinary subjects, but it is also disciplinary as each major core subject is covered in great depth, by world experts. At the time of preparation of this USER GUIDE, EOLSS has reached a size of about 66 million words.


The above simplified figure illuminates the essential interconnectedness of the twenty component encyclopedias of EOLSS.

 In the real world, the various knowledge domains do not exist in isolation from each other. They form an integrated whole, with links in all directions. It is well known that all forms of human knowledge are inter-connected and inter-related. EOLSS mimics this complexity, the automatic inter-connectedness of the various subject categories facilitating navigation through the vast landscape of EOLSS knowledge. This provides the user with an effective and efficient tool to search, navigate and browse through each of the component encyclopedias, through any combination of the Twenty, or through the whole of EOLSS.

Their titles and main contents are set out below. Within these Twenty One on-line encyclopedias, there are one hundred and eighty five Themes, each of which has been compiled under the editorial supervision of a recognized world expert. Each of these ‘Honorary Theme Editors’ was responsible for recruiting an appropriate selection of authors to produce the material specified by EOLSS. On average each Theme contains about thirty chapters. Most of the Themes have been completed but the virtual library will be augmented and updated on almost as often as every Month (augmenting refers to addition of new material and updating is the process of revising existing material to bring it up to date). About twenty Themes are still under development and are not yet available on-line

This Study Guide provides a road map to help the user find his/her way around EOLSS. It facilitates rapid identification and retrieval of the most relevant material. For example, university lecturers will find it useful in ensuring comprehensive coverage of their chosen subject, and an invaluable aid in lecture and seminar preparation. It can be used in research and preparation of study notes, papers, reports, theses, dissertations, etc. Every chapter is peer-reviewed to ensure that the contributions meet the required standards of comprehensiveness, clarity, coherence, and consistency and that the material is factually correct and helpful in self study

The EOLSS is designed to appeal to a wide spectrum of users from the merely curious to those seeking in-depth knowledge. To satisfy these, the EOLSS Contents have the following characteristics:

- Popular appeal by providing widely understandable perspective presentations.

- Educational relevance through presentations that emphasize knowledge principles, or fundamentals, and their applications.

- Professional utility through descriptions of knowledge practices and their applications.

- Research relevance through presentation of knowledge principles from the general to the very specialized.

- Future and policy orientation through provision of knowledge perspectives that are useful for obtaining forecasts of trends in science, technology, and social programs.

The chapters are generally at two or three distinct levels (1) broad overviews, perspectives, and introductions to major core subjects (or Themes such as Oceanography, Ecological Chemistry, Psychology, Control Systems and Robotics, Biotechnology, Archeology, etc.) generally targeted at non-experts, (2) comprehensive presentations introducing specialized areas within core subjects, and (3) in-depth presentations on various aspects of the core subjects.

The chapter level is indicated by the color of its title (see the related chapters).

Level 1: A chapter at this level introduces a core subject (or a field of knowledge) to a wide audience including undergraduates and non-expert readers needing to grasp the fundamental concepts. These chapters generally avoid the use of technical jargon or complex mathematics.

Level 2: A chapter at this level introduces a branch of the core subject (or a sub-field of knowledge) to be covered by a group of Level 3 chapters. The contributions are useful to senior undergraduate and postgraduate students as advanced study cum reference material.

Level 3: Most of the contributions in the EOLSS are at this level. These chapters cover different aspects of the sub-field in depth and contain relevant and necessary details of the established knowledge associated with it

EOLSS contains authoritative presentations from leaders and cutting-edge specialists in many fields. It can be used in research and preparation of study notes, papers, reports, theses, dissertations, etc. Excerpts from EOLSS materials may be freely copied and pasted, and used in non-commercial publications, with due acknowledgement to EOLSS.

2. The EOLSS Table of Contents EOLSS-bullet

The EOLSS Table of Contents lists the titles of the core subjects (Themes or Chapters at Level 1). If you click on ‘Knowledge in Depth’ at the end of any title, you will be taken to the detailed list of chapters in each core subject.

3. Access to the Full Text of the Desired Chapter(s) EOLSS-bullet

Access to the full text of the EOLSS is only arranged through Registration, either for a free trial or by subscription. Select the appropriate item under Login or Subscription .

Login or Subscription: EOLSS-bullet

Search: EOLSS-bullet

To assist the user to realize the full potential of the EOLSS Body of Knowledge, a powerful search feature is provided. This enables access to the chapter(s) closely matching the user needs and a list of related chapters. Using SEARCH WITH ALL OF THE WORDS, EXACT PHRASE or ANY OF THE WORDS in ALL SUBJECT CATEGORIES or in selected SUBJECT CATEGORIES; one can search the whole body of knowledge or selected parts of the Encyclopedia respectively. (A SUBJECT CATEGORY is a group of related core subjects or major fields of knowledge. For example, under the subject category MATHEMATICAL SCIENCES the following core subjects are grouped: Mathematics: History, Concepts, and Foundations; Mathematical Models of Life Support Systems; Computational Methods and Algorithms; Optimization and Operations Research; Probability and Statistics; Mathematical Models; Modern Biometry).

In addition to the above features the search also provides additional ways to find information and can help sharpen the search for results closely matching user needs.

Search results are organized according to the subject categories. Such presentation is possible in the EOLSS because of its thematically organized body of knowledge. On the other hand, a search in wilderness (e.g. the Internet) would not allow such convenience.

This feature is of great value in the exploration of interconnections between subjects.

Define a Query: EOLSS-bullet

Enter one or more search words, separated by spaces, in the input field and hit the Search button.

Three options are presented for telling the Search Engine how to interpret the query including more than one word. The default option is to search for all words; however the user is free to select any other option which is more suitable.

Search with all of the words:     EOLSS-bullet

Choose this option to find chapter documents that contain all of the words you entered. Chapters that contain only some of the words will not be returned. In Boolean terms, this is the same as conducting an "AND" search. In practice this is the preferred method for the majority of user queries.

Search with the Exact Phrase    EOLSS-bullet

Phrase Search allows a user to obtain exact matches. For example, by entering The Neurophysiological Basis of Pleasure, you will only find documents that include this precise phrase, not those that happen to have one or more of these words somewhere on the document. It is possible to go directly to a chapter by entering the exact title (taken from the Table of Contents) and selecting ‘Exact phrase’ as the Search Type.

Search with any of the words:   EOLSS-bullet

Choose this option to find all documents that contain at least one of the words you have entered. This is similar to conducting an OR search with other search engines. It is not necessary to formulate a Boolean expression using "and" "not" and/or "or" operators. In fact, our Search Engine will ignore these operators. This kind of search can be useful when the user needs information on an unusual combination of subjects and he/she is interested to see all the results, even if not all the terms are present in any single chapter.

Noise words       EOLSS-bullet

It is useful to remember that when using all words or any word as the search type, the Search Engine ignores "noise words". These are words that appear very often in a given language such as articles (a, an, the), conjunctions (and, or, but), forms of "to be" (is, was, are, etc.) and other common words. These are words that are likely to appear on a majority of documents. The Search Engine will consider these words only when the search type is exact phrase; an exact phrase search for Marie and Pierre Curie, would return all chapters that include the word "and".

Recognized Search Operators and Special Characters      EOLSS-bullet

Our Search engine does not recognize Boolean search commands such as +, -, and, or and not. These operators will be ignored by the search engine. Special characters such as , ‘ ’ “ ” ; ? ! : etc are not permitted and must be avoided. Using these characters may result in unsatisfactory search results.

Phonetic Search and Stemming EOLSS-bullet

Our search engine may suggest other search possibilities based on phonetic matching of search words. These functions will only suggest combinations that exist on the site. Stemming refers to grammatical deviations based on the search word and are implemented automatically. Therefore, should you search for 'development', our search engine will return results for 'develop' or 'developing' or ‘developed’.

Understanding your search results: EOLSS-bullet

The Search Engine assigns a SUBJECT CATEGORY to each chapter. If you would like to limit your search to a single SUBJECT CATEGORY, then select that SUBJECT CATEGORY in the search form. After you submit your search query, the result page appears, showing a summary of all of the chapters found by your query. From here, you can dig further into the list of documents returned, or click on a link to view a found chapter.

Subject Categories: EOLSS-bullet

By default, the 'Search all Subject Categories' option is selected. This will display an overview of the documents that best match your query with the list sorted by subject category. This makes it easier for you to find what you are looking for among a long list of results. From this list, which is arranged by subject categories, you are able to view all of the chapters found in each subject category.

The most relevant of the found chapters belonging to each subject category are listed below each headline. To the right of each subject category headline is a number indicating the total number of chapters that were found in that subject category. At the end of each subject category there is a link to the full listing of all of the chapters found in that subject category. To view a chapter, click on its title in the list.

Result Page Header EOLSS-bullet

At the top of the results page, there are several lines that provide general information about the search results. The information will vary according to the type of search you have made and the results found.

The following lines appear at the top of the results page:

Search             list of the actual search word(s).

Search Type   the search type option used such as all words, exact phrase or any words

Categories      the number of subject categories in which search word(s) were found.

Found              the number of documents in which search word(s) were found.

The results of a search will be a listing of titles of chapters, each with a short summary arranged according to the category from which it was retrieved.


Query: Consider the title of a chapter EPIDEMIOLOGY: HEALTH AND DISEASE IN POPULATIONS as a set of search words.

Result Page Header


Search Type: all words

Subject Categories: 14

Found: 198 document(s)

Below the Result Page Header will be found documents (titles of chapters with short summaries) listed according to Subject Categories. Such an organized presentation of search results, which is of great value in the exploration of interconnections between subjects, is possible in the EOLSS by virtue of its thematically organized body of knowledge. On the other hand, a search in wilderness (e.g. the Internet) would not allow such convenience.

The order of listing will be in the descending order of total number of occurrences of the sequence of the words EPIDEMIOLOGY HEALTH DISEASE POPULATIONS. The appearance of found documents with all words in more than one subject category is due to (i) the interdisciplinary nature of the subjects and (ii) the lack of binding between the words.

4. EOLSS Body of Knowledge EOLSS-bullet

To facilitate search in parts (in selected subject categories) the material is organized into twenty component encyclopedias (broad subject categories).

5. Mathematics

You can zoom in on any equation for an enlarged view by simply clicking on it. The zoomed equation appears sufficiently enlarged in a popup window. To zoom out re-click on the zoomed equation; the popup window vanishes and the normal view of the page is restored.

6. Cross-References EOLSS-bullet

Cross references take you to related chapters through links. You can go forward and backward between the cross referenced chapter and the original document page.

Related Chapters: provides a list of chapters in a popup window so that the reader is given a picture of what is available in the close neighborhood of the chapter on the screen, i.e. a list of chapters presented in a thematic organization. These results are helpful in providing you with a systematic access mechanism to the body of knowledge with reference to the search term inserted at the beginning, and to indicate a program of study in gradually increasing depth and detail).
At the bottom of this list ‘see also’ leads to chapters in other Encyclopedias in EOLSS that may also be of interest to you.

The Table of Contents of the whole EOLSS is so large that it is not easy to browse and systematically pick chapters of interest.