Use keywords to search for books and articles.
To get keywords, think about the main ideas of your topic.
For example: How does homelessness affect children in school?
Remember, computers will search for every word that you type into the search box, so try to keep your search simple - just a few words.
Now, let's take each of the main ideas (in red) and come up with some synonyms or related ideas:
homelessness -- without shelter, low income, poverty
children -- students
school -- education, academics, achievement
Do this with your topic, and you will have some keywords to begin your search with!
Next, combine any one of the keywords from each group using AND.
1. homeless students AND education
2. children AND poverty
Different combinations of keywords will give you very different results, so try several different searches to see which gives you the best results.