1. A. S. CARSLAW and J. C. JAEGER, “Operational methods in Applied Mathematics,” Oxford Univ. Press, New York, 1941.
2. L. PRANDTL and O. G. TIETJENS, “Fundamentals of Hydro- and Aero-mechanics,” McGraw-Hill, New York, 1934.
3. P. M. MORSE, “Vibration and Sound,” pp. 233–248. McGraw-Hill, New York, 1948.