1[4]P. H. Spencer, S. Monica, Calif, 1958, "Toy Airplane," United States Patent Office 2859553.
2[7]H. S. Yan, 1998, Creative Design of Mechanical Devices, Springer-Verlag, Singapore.
3[9]H. S. Yan, Y. W. Hwang, 1988, "The Generalization of Mechanical Devices," Journed of the Chinese Society of Mechanical Engineers, Vol9, No. 3, pp.191-198.
4[10]H. S. Yan, L. C. Hsieh, 1989, "Concept Design of Planetary Gear Trains for Infinitely Variable Transmission," International Conference on engineering Design, Harrogate, United Kingdom, pp.757-766.