De biologie van de angelloze bijen / samengest. door Hayo H.W. Velthuis ; met medew. van: J.C. Biesmeijer ... [et al.]The biology of stingless bees / prepared by Hayo H.W. Velthuis ; in cooperation with: J.C. Biesmeijer ... [et al.]Biologia das Abelhas sem Ferrão / organizado por Hayo H.W. Velthuis ; com colaboração de: J.C. Biesmeijer ... [et al.]