Check this tutorial out for tips on how to use ProQuest's Advanced Search:
By default, when you search ProQuest, you will get eBook results in addition to all of your other results in a separate tab at the top of the results list. If you are looking for eBooks, click on the "Ebook Central results" tab.
You might get a lot of book reviews included in your results. If that annoys you, you can get rid of them! Click on "More options..." under the "Document Type" tab along the left side of your results list (you will probably have to expand the Document Type tab first).
This will open up a window that will allow you to exclude reviews from your search results: just check the "Exclude" box and hit "Apply" in the bottom right corner of the pop-up window to update your list!
Adjust the databases that ProQuest will search for you. Either add or remove databases to broaden or narrow your results. Click "Databases" near the top of the search results screen to open up a list of the databases ProQuest searched through with your search terms.
Select or de-select the databases you want to include or exclude from your search, and click "Use selected databases" back at the top of the list. You will have to rerun your search if you decide to update or change your databases from the search results list.