1. Hutton, F. W., Ibis, 1, 276 (1865).
2. Andersson, C. J., Ibis, 2, 324 (1866).
3. Chapman, F. R., Trans. N.Z. Inst., 23, 491 (1891).
4. Buller, W. L., “Supplement to the Birds of New Zealand” (London, 1905).
5. Matthews, L. H., “Birds of South Georgia”, Discovery Reports, 1, 563 (1929).