The chief work on the internal anatomy of Hemiptera is still Dufour's Recherches anatomiques et physiologiques sur les Hémiptères, Mem. Savans Étrangers, Paris, iv. 1833, p. 129.
Künckel, Ann. Soc. ent. France (4) vii. 1867, p, 45, and C.R. Ac. Paris, cxx. 1895, p. 1002.
In Slingerland's Cornell Univ. Bull. No. 58, 1893, p. 222.
SB. Ak. Wien. xci. 1 Abth., 1885, p. 275.
Les Insectes fossiles, etc., 1894, p. 452.