Stuart J. Murphy. (1997). "Betcha! Estimating (Mathstart, Level 3)". HarperCollins.
Chicago-čujuhus (17. p.)Stuart J. Murphy. "Betcha! Estimating (Mathstart, Level 3)". HarperCollins, 1997.
MLA-čujuhus (9. p.)Stuart J. Murphy. "Betcha! Estimating (Mathstart, Level 3)". HarperCollins, 1997.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.