Festschrift Ges. naturf. Freunde Berlin, 1873.
Reference may be made to Calvert's recent paper introductory to the study of Odonata, in Tr. Amer. ent. Soc. xx. 1893, pp. 159-161.
Horae Soc. ent. Ross. xvi. 1881, p. 3.
Physiol. facett. Aug. 1891, p. 115.
Bull. Ac. Belgique (3), xvi. 1888, No. 11, p. 31.