Or, if you're a stickler, Indices.
When I first got hooked on Henry Reed, I didn't really know how to go about tracking down sources. There was Granger's Index, sure; and the fledgling Internet helped a little (although, a lot of stuff was still being released on CD-Rom, at that time. Ah! The 'Nineties.). Mostly, I was following breadcrumbs: the footnotes in one article would lead me to two others, which led me to three others, et cetera, et cetera, ad infinitum. I'm proud that I did it that way. It was hard work. Detective work.
But recently, I discovered a lot of time and effort could have been saved had I just spent a couple of afternoons and evenings going shelf by shelf, title to title, in the Reference section of the university library.
Reed is hardly obscure. The Lessons of the War and "Chard Whitlow" are widely anthologized. His radio work for the BBC placed him in another milieu entirely, an extensive range. I'm convinced that you cannot swing a cat, living or dead, in any library with the Library of Congress call number "P," without hitting a book that mentions Reed.
So, taking Vizzini's advice, I go back to the beginning. To see if there was anything I missed.
I've spent the last few evenings after work prowling indexes for never-before seen citations: anthologies, biography, explication, and just plain passing mention. I'm literally tanned from standing over an open photocopier, repeatedly turning heavy volumes on the glass like steaks on a barbeque.
The latest Granger's Index to Poetry was the largest boon, naming at least a dozen anthologies to track down and look up. The library has a 2002, 12th edition, whereas at home I'm stuck with an 8th that I plucked from the donation box of the first public library I worked for (I miss getting first paws on the duplicates donated to the Public Library System. Sigh). The 12th actually has an entry for Reed's "Dull Sonnet," which is obscure enough that even I had to go look it up.
But I also turned up the index to a set called Modern British Literature, compiled and edited by Ruth Z. Temple, et al. Alas, the university only owns the American half of the series. I see a field trip in my future.