H. S. Swarth, 1935, _Condor_, Vol. 37, p. 84 (barn swallows). M. A. Common, 1942, _Auk_, Vol. 59, p. 43 (tree swallow). D. L. Serventy and H. M. Whittell, 1948, _Birds of Western Australia_, p. 243 (welcome swallow).