Free, J. B. and Simpson, J. 1968. The alerting pheromones of the honeybee. Zeitschrift fur vergleichende Physiologie. 61 (3), pp. 361-365. https://doi.org/10.1007/BF00428008
Simpson, J. 1964. The mechanism of honey-bee queen piping. Zeitschrift fur vergleichende Physiologie. 48, pp. 277-282. https://doi.org/10.1007/BF00339456