1. Farrar C.L. (1953) Two queen colony management. Bee World 34, 189–194.
2. Loubet de l’Hoste E. (1959) La biruche. Laubet de 1’Hoste, Toulouse.
3. Holzberstein J.W. Jr (1955) Some whys and hows at two queen management. Glean. Bee Cult. 83, 344–347.
4. Wafa A.K. (1956) Two queen colonies for a plentiful yield of honey, safe wintering, means of propagation and swarming control. Bull. Fac. Agr. Cairo Univ, 98, 22.
5. Wallrebenstein W. (1955) Mein Beitrag zum Mehrmutterverfahren. 17th Int. Beekeep. Congr.