1. M. K. Barnoski, ?Fundamentals of Optical Fiber Communications?, (Academic Press, Inc., New York, San Francisco, London, 1976), Ch. 3 p. 83.
2. H. F. Wolf, ?Handbook of Fiber Optics: Theory and Application?, (Garland STPM Press, New York, London, 1979) p. 139.
3. W. B. Allan, ?Fibre Optics Theory and Practice?, (Plenum Press, London, New York, 1973).
4. Technical staff of CSELT, ?Optical Fibre Communication?, (CSELT, Torino, 1980).
5. N. S. Kapany, ?Fiber Optics?, (Academic Press, New York, 1967).