>Germany submitted 24 volume set under the title "Introduction into elephantology."

I can subscribe to this one.

Back in the 70's, in my second year at med school I found a german book on histology (how cells organize themselves to form tissues, which for organs in the body).

It was book 8 in volume 4 of the "Handbuch der Histologie des Menschen" ("Handbook of human histology"). Volume 4 covered the human nervous system. Book 8 consisted of 800 pages covering allocortex, one of the 3 types of cerebral cortex in humans.

I never found out the total number of books and pages.