Ellis, Beth; Daly, Douglas C.; Hickey, Leo J.; Mitchell, John D.; Johnson, Kirk R.; Wilf, Peter; Wing, Scott L. Cornell University Press 2009 Pehmeäkantinen kirja
Moore, Melinda; Wermuth, Michael A; Resnick, Adam C; Green, Harold D; Broyles, James R; Hickey, Scot; Ostwald, Jordan; Leuschner RAND Corporation 2012 Pehmeäkantinen kirja