APA (7th ed.) Citation

National Council of Teachers of Mathematics, Velasco Coba, F., & Lluis Riera, E. (1970). Geometría informal. Editorial Trillas.

Chicago Style (17th ed.) Citation

National Council of Teachers of Mathematics, Federico Velasco Coba, and Emilio Lluis Riera. Geometría Informal. México: Editorial Trillas, 1970.

MLA (9th ed.) Citation

National Council of Teachers of Mathematics, et al. Geometría Informal. Editorial Trillas, 1970.