The system defaults to 1980 to present. Compendex allows a high degree of sophistication for searching and retrieving information. Very specific fields can be search independently. Be resourceful .choose the words that best express your topic. You can truncate words and make your search more general or use words that are more specific.
Every file is different distinct.
Use more than one electronic file to get a broader focus, perspective, coverage, bias, etc. You have access but will not always have availability. Carlson Library only owns a small percentage of the citations you will be able to access. This is a FREE service but can take up to two weeks to get you the article. Like any skill, the more you use each of the electronic databases that better search results you can retrieve.