A term coined by Information scientist Eugene Garfield to refer to the situation in which works (particular scientific works) are so well known in a field they are no longer cited. For example in modern research articles on relativity, Albert Einstein is cited relatively rarely and usually only when a direct quote is used from one of his works.

The phenomenon is caused by a number of things, the founding publications in a field are rarely pedagogically oriented so they're not widely used in the classroom. A rare except to this is perhaps the K&R C book by Brian Kernighan and Dennis Ritchie called The C Programming Language.

source: http://www.garfield.library.upenn.edu/essays/v2p617y1974-76.pdf