REFERENCES
- P. Appell, Traité de Mécanique Rationnelle, vol. 1, 6th ed., Gauthier-Villars, Paris, 1941.
- B.Y. Chen, Geometry of Submanifolds, Marcel Dekker, New York, 1973.
- D. Laugwitz, Differential and Riemannian Geometry, Academic Press, New York, 1965.
- R. S. Millman and G. D. Parker, Elements of Differential Geometry, Prentice-Hall, Englewood Cliffs, NJ, 1977.
- D. A. Singer, Curves whose curvature depends on distance from the origin, this Monthly 106 (1999) 835–841.
- D. J. Struik, Differential Geometry, 2nd ed., Addison-Wesley, Reading, MA, 1961.
- J. L. Weiner, How helical can a closed, twisted space curve be?, this Monthly 107 (2000) 327–333.