Supernatural Horror in Literature is an essay style work written by H.P. Lovecraft. It details the top works and writers of "Supernatural Horror" and "Weird Literature", at least, according to H.P. Lovecraft. He goes over their faults as well as the things that make them unique and worth reading. In many cases, the things that Lovecraft mentions as being good or of high quality were those things he himself wished to better emulate in his own writing.
They also give a good basis of what are the influences on Lovecraft's writing.