REFERENCES
- Goldsmith, W. (1960). Impact. London; Edward Arnold.
- Hocknell, A., Galloway, J.A. and Hehnatetter, R.C. (1999). Set of woods with face thickness variation based on loft angle. United States Patent Application Number 09/431,982.
- United States Golf Association, USGA (1999). Procedure for measuring the velocity ratio of a club head for conformance to Rule 4-Ie, Appendix II. Revision 2. Far Hills, NJ: USGA.