Stealthy invaders: the biology of Cardiocondyla tramp ants
J. Heinze, S. Cremer, N. Eckl, A. Schrempf, Insectes Sociaux 53 (2006) 1–7.

A transitional stage between the ergatoid and winged male morph in the ant Cardiocondyla obscurior
S. Cremer, B. Lautenschläger, J. Heinze, Insectes Sociaux 49 (2002) 221–228.