Ney, Andrei. “Structures algébriques à élément Fixe Qui modélisent De Divers phénomènes: Fixed-Element Algebraic Structures That Model Various Phenomena”. Rev. Anal. Numér. Théor. Approx., vol. 26, no. 1, Aug. 1997, pp. 165-77, https://ictp.acad.ro/jnaat/journal/article/view/1997-vol26-nos1-2-art22.