Ann. Nat. Hist. (4) vi. 1870, p. 225.
A table of the families is given by Ashmead, but does not work out quite satisfactorily, Entom. Americana, iv. 1888, p. 65; a brief table of the characters of the British families is given by Saunders, Hemiptera-Heteroptera of the British Islands, 1892, p. 12.
Those who wish to see tables of the families are referred to Ashmead, loc. cit.; to Pascoe, Ann. Nat. Hist. (5) ix. 1882, p. 424; to Stål's Hemiptera Africana, vol. iv. 1866; and for the families found in Britain to Edwards, Hemiptera-Homoptera of the British Islands. For a discussion in Danish on the value of the characters used, cf. Hansen, Ent. Tidskr. xi. 1890, pp. 19-76.
Ent. Mag. vii. 1870, p. 53.
Insect Life, i. 1889, p. 234.