Kolby, J. &. o. (2015). GMAT: DATA Sufficiency Prep Course. Prakash Pub.
Chicago-čujuhus (17. p.)Kolby, Jeff & others. GMAT: DATA Sufficiency Prep Course. New Delhi: Prakash Pub, 2015.
MLA-čujuhus (9. p.)Kolby, Jeff & others. GMAT: DATA Sufficiency Prep Course. Prakash Pub, 2015.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.