1. Nottebohm, F. Origins of vocal learning. Am. Nat. 106, 116–137 (1972).
2. Kroodsma, D. E. Acoustic Communication in Birds eds Kroodsma D. E., Miller E. H. 311–337Academic Press: New York, (1982).
3. Konishi, M. The role of auditory feedback in the control of vocalization in the white-crowned sparrow. Z. Tierpsychol. 22, 770–783 (1965).
4. Marler, P. & Peters, S. Subsong and plastic song. Acoustic Communication in Birds 25–50Academic Press: New York, (1982).
5. Nottebohm, F., Stokes, T. M. & Leonard, C. M. Central control of song in the canary, Serinus canaria. J. Comp. Neurol. 165, 457–486 (1976).