- document
- Letcher, John S. (author), Cressy, C.P. (author), Oliver, J.C. (author), Fritts, M.J. (author) journal article 1987
- document
- Letcher, John S. (author), Cressy, C.P. (author), Oliver, J.C. (author), Fritts, M.J. (author) conference paper 1987