WITUŁA, R.; HETMANIOK, E.; SŁOTA, D. Ma’s identity and its applications. Annales Universitatis Paedagogicae Cracoviensis Studia Mathematica, [S. l.], v. 11, p. 43–52, 2012. Disponível em: https://studmath.uken.krakow.pl/article/view/13209. Acesso em: 31 oct. 2026.