Research is often not a straight line from point A to point B but rather exploration. Trial and error may be involved!
You will definitely be asking and answering a series of questions along the way:
Using Credo, you can search a general topic such as SUFFRAGE and find articles and occasionally photos from many different encyclopedias and other reference works that help you get a "big picture" understanding of the topic.
You can add relevant search terms using AND to check for more focused information.
Combining search terms with AND shows you just the results that have both terms or sets.
You can then use Interlibrary Loan to borrow books etc. from other libraries if ISU doesn't own them.
Just logon to ILLiad (that's the name of ISU Library's Interlibrary Loan service). First time users will be led through account setup process; then type in the title, author, etc of the item you found in WorldCat. Submit the form! You'll be notified within a few days when your item arrives and where you can pick it up - usually at the Parks Library Circulation Desk.