Recently, we had a question on the philosophy stackexchange:
that included two quotes from the Tractatus. I had suggested the references be added. This led to the following two discussions:
Where at least two of our users don't see the value in adding them, because the quotes are (1) well-known and (2) able to found with simple google searches.
What does the community think about expecting people to put a reference when quoting (when possible)?