Junior Lecturer, University of the Witwatersrand, Johannesburg, South Africa, 1968-1970.
Teaching Assistant, McMaster University, Hamilton, Ontario, Canada, 1971-1975.
Assistant Professor, University of Georgia, Athens, Georgia 30602, U.S.A., 1975-1981.
Associate Professor, University of Georgia, Athens, Georgia 30602, U.S.A., 1981-1987.
Professor, University of Georgia, Athens, Georgia 30602, U.S.A., 1987-present.
PH.D. AND M.A. ADVISEMENT
| Student | First College Position |
| Chin-hong Sun, (1986) | National Taiwan University, Taiwan. |
| Jerry Davis, (1987) | San Francisco State University |
| Keun Bai Yu, (1986) | Seoul National University, S. Korea |
| Rudi Kiefer, (1986) | University of North Carolina at Wilmington |
| Robert Hyatt, (1984) | Radford University |
| Zhi-Yong Yin, (1990) | Georgia State University |
| Joseph Garcia, (1992) | University of South Florida |
| Steve Harper, (1996) (Geology) | East Carolina University |
| Thomas Feeney (1997) | Shippensburg University |
| Heidi Lamoreaux (1999) | Sonoma State University |
| Sydney Bacchus (Ecology) (1999) | |
| James Webster (2000) | |
| Shaw-Wen Sheen | National Tainan Teacher's College, Taiwan |
| Honglin Xiao |