- Clason, T. R. 1978. Utilization of paraquat in a silvicultural thinning regime: first year results. Pages 14-18 in M. H. Esser (ed.), Proceedings of the annual meeting of the Lightwood Research Coordination Council. United States Department of Agriculture, Forest Service, Southeastern Forest Experiment Station.
- Clason, T. R. 1979. Paraquat induced oleoresin biogenesis in a thinned loblolly pine stand: second year results. Pages 104-106 in M. H. Esser (ed.), Proceedings of the annual meeting of the Lightwood Research Coordination Conference, 17-18 January, Atlanta, Georgia, Asheville, North Carolina. United States Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 151 p.