HOUGHTON, Holly V.; ARRINGTON, Larry R.; BRADSHAW, Joan P. Effectiveness of Correspondence Instruction in an Extension Vegetable Gardening Program. Journal of Agricultural Education, [S. l.], v. 35, n. 1, p. 21–25, 1994. DOI: 10.5032/jae.1994.01021. Disponível em: https://jae-online.org/index.php/jae/article/view/2109. Acesso em: 23 jun. 2026.