Oldak Quill wrote:
Let me give you an example. If I were writing an
article on a drug and
I included the sentence "tyrosine is an amino acid", I would be
expressing a relation that is learnt in secondary education. It being
an amino acid is the first thing anyone would learn about tyrosine. Is
this reference worthy?
Yes. Either you have a one-sentence stub article, in which case its
one required reference could be almost any textbook or webpage
mentioning tyrosine, or else you have additional material in the
article, whose required source will also happen to mention tyrosine's
amino-acid-ness.
Incidentally, one of the interesting side-effects of looking up
references is that one regularly discovers that the "common
knowledge" from secondary education days is now many years out
of date, and no longer correct.
Stan