How do you find historians opinions and secondary sources?

by BarrackOsama122

Hello, I am currently writing an essay on the influence of Domino Theory in Vietnam and to counter it I have been using Quagmire Theory as my example. However I am running low on secondary sources, I am wondering if anyone has a good way of finding legitimate opinions of professional historians on the topic that I could quote, such as A.Schlesinger or L.Gelb. Thank you for helping

voyeur324

/u/caffarelli has previously explained about finding secondary sources for a 'Monday Methods' post.

/u/sunagainstgold has previously written about:

See also the subreddit booklist Maybe /u/Velken will be able to offer more specific suggestions.

I would generally start by looking at the bibliographies of the books you've already read, and note which secondary sources are used by multiple books, then read those books, and so on. Pay attention to how those sources are used in the text, since not every citation is made because the source is good. Sometimes books are cited so the author can pick a fight with other historians.