Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.

BIOL 700 Research and Thesis: Advanced Search Strategies

This guide offers advanced tips and resources for acing your thesis research


"To thoroughly research the literature on a subject, one must pursue various avenues and strategies to identify relevant scholarship. As a rising tide fills the salt marsh through its channels, creeks, and branches so must a search strategy probe the literature through the obvious, the subtle, and the unexpected."   Geoff Timms, philosophical and poetic in the pre-coffee morning mist

Pearl Growing - Expand your result set based upon initial results

If your initial searches don't yield many results or you sense that you're not managing to capture all relevant articles in your results, consider the Pearl Growing search strategy. This involves using a relevant article record to identify key information which can be used to enhance your search. Like the layers of a pearl form cumulatively, your search will develop in phases as you identify more relevant articles.

An article record found in databases usually includes

  • controlled vocabulary or SUBJECT terms
  • an abstract,
  • author list
  • cited references (cited by this paper) - these will predate the current paper
  • citing references (citing this paper) - these will postdate the current paper

Look for terms in the abstract and the controlled vocabulary or subject terms, which might help you expand your search (see 'Using the Boolean OR' below).

Pearl growing may also used the cited or citing references available for a given paper. Web of Science offers particularly comprehensive citation searching (or tracking, as you don't really do a new search as much as you 'follow the citation trail'). The following video demonstrates pearl growing by citation tracking in Web of Science.


Using the Boolean OR

Use OR to add alternative conditions to your search. At least one of the terms must be matched for an article to appear in your results.

When to use OR:

  • You have varied, even unrelated, criteria any one of which would be useful if matched in your results
  • Synonyms exist for a concept you want represented
  • Your initial search yielded too few results
  • You suspect your initial search caused relevant articles to be excluded from your results

e.g. You are researching Red Drum which have various names, both scientific and common. Your search might look something like:

Sciaenops ocellatus OR red drum OR spottail bass

Boolean OR

Things to expect by adding conditions with OR:

  1. The number of results will usually increase with every alternate condition you add to the search
  2. The relevance of your results may decrease because of the alternate criteria you have chosen

Hot Tip!

Look at the subject categories assigned to an article in the article record. You may discover new terms that can be used as synonyms or alternative search criteria.

Facets - Narrow or focus your search

If your initial searches yield an excessive number of results, consider further refining your search to increase its relevance and to further focus the result set.

Selection of Web of Science and ProQuest facets listed with result sets after searching for "Red Drum"

Web of Science FacetsProQuest Facets

These facets offer many opportunities for refining your search. Web of Science Categories and Research Areas as well as ProQuest Subject and Classification relate to subject area and are very useful. Geographic facets help you focus on a particular region or country, while organization and funding agency facets can be useful for tracking grant funded research.

Follow the author's scholarship

Researchers often devote substantial effort to a particular species, problem, phenomenon, or theory. If one article of a particular researcher or team of researchers is of value to you, it is worth investigating other scholarship by these authors.

The following video demonstrates the finer points of author searching on Web of Science. The initial principles applied are valid in multiple databases, but Web of Science also has a unique author search tool which is demonstrated in this video


As a developing professional, you may wish to contact the author to ask questions. Find the author's most recent work in an online database like Web of Science or ProQuest Science and Technology Collection and look for contact information or institutional affiliation. You can then search for the author at the university, institute, or organization listed for the recent article.

Researchers are usually passionate about their work and more often than not they will be pleased to communicate with you personally. Remember to be professional in your communication with the author and maintain an appropriate level of interaction.