The famous 'Bleiler Checklist' comes in two very different editions with distinct titles. First is The Checklist of Fantastic Literature; A bibliography of Fantasy, Weird and Science Fiction books published in the English language issued in 1948 (with an unauthorized reprint in 1972). Thirty years later it was thoroughly revised and expanded (600 titles dropped, 1150 titles and much new info added)
and the title was changed to The Checklist of Science-Fiction and Supernatural Fiction. Both versions cover roughly the same period, 1800-1948, but, in Bleiler's own words, the 1978 book "is a revision so extensive that it really constitutes a new book."

So, please do not combine the two checklists. The Checklist of Fantastic Literature; A bibliography of Fantasy, Weird and Science Fiction books published in the English language and The Checklist of Science-Fiction and Supernatural Fiction are different 'works' and should be kept separate.