Preparations for information search
Choose the search terms so that they describe the topic as well as possible.
You can use tools for searching and choosing the search terms; for example:
- dictionaries, vocabularies and word lists
- keyword and index term lists in reference publications
- any articles already found on the same topic
Check the synonyms and abbreviations for the search terms. Check also the spelling (cf. am. English and br. English).
Keywords are words which describe the topic and which have been freely extracted from the text. Index terms or descriptors are term lists which have been collected into vocabularies to be used for describing systematically the content of the publication. Using index terms and descriptors gives a more comprehensive result than using randomly chosen keywords but e.g. fashionable terms and terms describing new innovations appear into index term lists with a delay of even years.
Various classifications and codes can be used with or in stead of search terms. They however differ between publications and databases. Check these for each source before using them
Search profile or combining the search terms or search logic
The search terms are combined according to Boolean logic with operators AND, OR and NOT so that they describe the topic in the best possible way. You should avoid using the operator NOT because it may remove also good, important references from the set. It is good to use brackets. The search profile can also be aimed at a certain field cf. title. The search profile can also be limited to a certain period of time (cf. 2000-2010), a type of publication or language.
Index terms and the thesaurus
The publishers of databases and index and abstract publications use index terms for describing the content of a resource. A list is usually made of them where it is possible to choose those that correspond best one's own topic. In the search they function as classification codes i.e. they extract all such documents for the describing of which's content this certain index term has been used. The list of index terms can usually be found in the database and cf. the printed Chemical Abstracts includes a separate CA headings lists publication. If this list of index terms is organised hierarchically it is called a thesaurus. Using index terms gives a better search result so using them is very recommendable.