1. 1) A. Baines, Woodwind Instruments and Their History (Faber and Faber Ltd., London, 1957).
2. 2) A. H. Benade, Fundamentals of Musical Acoustics (Oxford University Press, New York, 1976), Chap. 21.
3. 3) C. J. Nederveen, Acoustical Aspects of Woodwind Instruments, 2nd ed. (Northern Illinois University Press, DeKalb, Illinois, 1998) pp. 50-53, 132-133.
4. 4) J. Wolfe and J. Smith, ``Cutoff frequencies and cross fingerings in baroque, classical, and modern flutes,'' J. Acoust. Soc. Am., 114, 2263-2272 (2003).
5. 5) N. H. Fletcher and T. D. Rossing, The Physics of Musical Instruments, 2nd ed. (Springer-Verlag, New York, 1998), Sects. 16.9, 15.3, 8.2, 4.10.