In the past, if you needed sources for a paper or for ideas, a professor would tell you to go look up your topic in Psychological Abstracts. Your library might still have the older bound volumes around. Psych Abstracts (as it was called) was a monthly periodical that reproduced the abstracts (short summaries) from journal articles. At the end of the year - a topical index was published that gave a number for each abstract. It was hellish to use.
Today there are options that are more modern.