A. C. Bent, 1938, _U. S. Natl. Mus. Bull._ 170, pp. 384-86, 398
(burrowing owl). H. Friedmann, 1930, _Natural History_, Vol. 30, p.
205 (social weaver). W. H. Hudson, 1920, _Birds of La Plata_, Vol.
2, p. 31 (monk parrot). W. R. B. Oliver, 1930, New Zealand Birds,
p. 118 (_Sphenodon_).