Johnston, C. (1987). Developmental mathematics (2nd ed.). Wadsworth.
Chicago-čujuhus (17. p.)Johnston, C.L. Developmental Mathematics. 2nd ed. Belmont, Calif: Wadsworth, 1987.
MLA-čujuhus (9. p.)Johnston, C.L. Developmental Mathematics. 2nd ed. Wadsworth, 1987.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.