- Ballard, E. 1921. Additions and corrections to the list of crop-pests in South India Report of the Proceedings of the 4th Entomological Meeting at Pusa 1921. 21-28.
- Ballard, R. G., M. A. Walsh, and W. E. Cole. 1980. Beetle kill in the lodgepole pine . Utah Science 41:78-81.
- Ballard, R. G., M. A. Walsh, and W. E. Cole. 1982a. A light and electron microscope study of the growth and development of blue stain fungus in sapwood of lodgepole pine [abstract] . Phytopathology 72:930.
- Ballard, R. G., M. A. Walsh, and W. E. Cole. 1982b. Blue-stain fungi in xylem of lodgepole pine: a light-microscope study on extent of hyphal distribution . Canadian Journal of Botany 60:2334-2341.
- Ballard, R. G., M. A. Walsh, and W. E. Cole. 1984. The penetration and growth of blue stain fungi in the sapwood of lodgepole pine attacked by mountain pine beetle . Canadian Journal of Botany 62:1724-1729.