KRISTENSEN, Leif. On a Cartan Formula for Secondary Cohomology Operations. MATHEMATICA SCANDINAVICA, [S. l.], v. 16, p. 97–115, 1965. DOI: 10.7146/math.scand.a-10751. Disponível em: https://tidsskrift.dk/math/article/view/10751. Acesso em: 14 aug. 2026.