Identification of oxygen containing volatiles in cephalic secretions of workers of brazilian stingless bees - Francke, Wittko; Lübke, Gunther; Schröder, Wolfgang; Reckziegel, Aurélia; Imperatriz-Fonseca, Vera Lucia; Kleinert, Astrid de Matos Peixoto; Engels, Elisabeth; Hartfelder, Klaus; Radtke, Rainer; Engels, Wolf (Journal of the Brazilian Chemical Society, 2000)