1
by Barnes, David, Roitzheim, Constanze
Published 2020
Cambridge University Press
... that is scattered across books, articles and decades. There is much folklore but very few easy entry points...

2
by Ulrich, Hanno
Published 1988
Springer Berlin Heidelberg
.... Among the consequences of the sum formula are some Borsuk-Ulam theorems as well as some folklore results...

3
by Ranicki, A.A., Casson, A.J., Sullivan, D.P., Armstrong, M.A.
Published 1996
Springer Netherlands
... several other results which have become part of the folklore but of which proofs have never been published...