1. GIBSON , G. A. , 1946 ,An Elementary Treatise on the Calculus( Macmillan & Co. Ltd. ), Exercise 20 , p. 480 .
2. KORN , G. A. , and KORN , T. M. , 1961 ,Mathematical Handbook for Scientists and Engineers( McGraw-Hill Co. ), p. 306 .
3. Inhomogeneous Coherent Magnetization Rotation in Thin Magnetic Films
4. Magnetic film memories, a survey