@article{somerville_sowell_1992, title={Object-oriented systems for machinery management}, number={92-7033}, journal={Paper (American Society of Agricultural Engineers)}, author={Somerville, G. D. and Sowell, R. S.}, year={1992}, pages={16} }
 @article{somerville_sowell_1992, title={Total farm machinery costs program for MS-Windows}, number={92-3043}, journal={Paper (American Society of Agricultural Engineers)}, author={Somerville, G. D. and Sowell, R. S.}, year={1992}, pages={15} }