Treasury format was an oversized soft-cover format which was seen a few times in the 70's. Awkward to store properly, these are not expensive, but it is hard to find them in good condition now.
Regarding the Superman crossover, note also the second Superman/Spider-Man crossover from 1981 in Marvel Treasury Edition #28.
|Editor:||E. Nelson Bridwell, Julius Schwartz, Marv Wolfman, Roy Thomas|
|Reprinted In:||Superman vs. Amazing Spider-Man (Gold)|