(8163) VAN LANGEN R„ 1973. Libellenverslag. – [Dragonfly report]. In: D. van Hummel, [Ed.]. De Mariapeel zomerkamp 1973, p. 26, Veren. Natuurstud. "Tuuma”, Amsterdam. (Dutch). A list of 10 spp., collected during a Youth Federation summer workshop in the Mariapeel, a part of the Peel swamps, the Netherlands. — For a comprehensive monograph on the odon, fauna of this wetland complex cf. OA 6961.