Obfuscation 101

I'm looking for some medical information and I come across a page on the NCBI (National Center for Biological Information) website. The page might have good information, but when was it published? I examine the page but I cannot find anything that looks like a date. There are a bunch of numbers that might mean something to someone, but they don't mean anything to me. So I inquire. In short order I got a response, which was of no help, but after some more back and forth I finally learn that

Acta Orthop Belg. 1991;57(4):399-405

means that

The citation indicates that this article was published in 1991:
Journal: Acta Orthop Belg. (an abbreviation for "Acta orthopaedica Belgica")
Year: 1991
Issue(Volume): 57(4)
Page number range: 399-405.
This is common format for scientific citations.

Obvious - not. What is obvious is that the scientific publishing community might as well be a secret society. They already have obscure notations, now all they need is a secret handshake.