National Council of Teachers of Mathematics, U.S.A. (1970). Geometría informal. Trillas.
Chicago-čujuhus (17. p.)National Council of Teachers of Mathematics, U.S.A. Geometría Informal. Ciudad de México: Trillas, 1970.
MLA-čujuhus (9. p.)National Council of Teachers of Mathematics, U.S.A. Geometría Informal. Trillas, 1970.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.