Robertson, W. C. (2002). Energy. NSTA Press.
Chicago-čujuhus (17. p.)Robertson, William C. Energy. Arlington, Va.: NSTA Press, 2002.
MLA-čujuhus (9. p.)Robertson, William C. Energy. NSTA Press, 2002.
Muitte dárkkistit čujuhemiid riektatvuođa, ovdal go geavahat daid iežat deavsttas.