JAPÓN, Maria, MALEC, Marek and PIASECKI, Łukasz. Short proofs of Cambern’s 1968 theorem and its generalizations applicable to fixed point theory. Topological Methods in Nonlinear Analysis. Online. 26 November 2025. Vol. 67, no. 1, pp. 87 - 102. [Accessed 18 May 2026]. DOI 10.12775/TMNA.2025.038.