JSTOR can be used to find secondary sources written by historians by setting the publication date from 1985 to the present - and by selecting the "History" discipline located towards the bottom of the page.
OneSearch is - in part - the UNI Library catalog. OneSearch can be used to find both older books (primary sources) and newer secondary source books written by historians. OneSearch connects you to roughly on million print books and hundreds of thousands of ebooks.