Simmons, G. (2007). Billions of missing links. Harvest House Publishers.
Chicago-čujuhus (17. p.)Simmons, Geoffrey. Billions of Missing Links. Eugene, OR: Harvest House Publishers, 2007.
MLA-čujuhus (9. p.)Simmons, Geoffrey. Billions of Missing Links. Harvest House Publishers, 2007.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.