To build an effective search for a database it is best to use keywords instead of phrases.
A good strategy for building a keyword search is:
1. Develop a clear topic statement
2. Draw out the concepts from the topic statement
3. Create a list of synonyms for each of the principal concepts
4. Conduct searches using the keywords and synonyms you have selected for an Advanced Keyword search
5. Add more synonyms to your list as you encounter them in your research
Use the Keywording worksheet (link to file above) to help with this process.