While the invention of a standardised citation index in 1961 was a consciously planned act, the practice of more or less standardised reference habits, which is a silent convention, is of course much older. It emerged spasmodically and unsystematically in isolated fields of the natural sciences in the second half of the 19th century. The convention was (and still is) based on the ethical principle that private individual claims to new knowledge, discoveries for instance, must be offered as potential public knowledge to the professional community. At the same time it was assumed in this convention that knowledge grows cumulatively by accretion. Our next problem is this: what happens to these practices in a situation of proliferation, outwardly indicated by the dilemma that specialists in numerous fields are no longer able to keep abreast in their own specialisation, yet must continue to provide references of relevant previous researches?