Morton, J.D., A.D. Stafford, A.G. Gillingham, A. Old, and O. Knowles. “The Development of Variable Rate Application of Fertiliser from a Fixed Wing Topdressing Aircraft”. NZGA: Research and Practice Series 16 (January 1, 2016): 163–167. Accessed April 18, 2026. https://www.nzgajournal.org.nz/index.php/rps/article/view/3247.