Morselli, Mariafranca; Whalen, M Lynn (1996). "Appendix 2: Maple Chemistry and Quality". In Koelling, Melvin R; Heiligmann, Randall B (eds.). North American Maple Syrup Producers Manual. Bulletin. Vol. 856. Ohio State University. Archived from the original on 29 April 2006. Retrieved 20 September 2010.
Saupe, Stephen. "Plant Physiology". College of Saint Benedict and Saint John's University. Retrieved 3 April 2018.
doi.org
Marschner, H (1983). "General Introduction to the Mineral Nutrition of Plants". Inorganic Plant Nutrition. Encyclopedia of Plant Physiology. Vol. 15 A. Springer. pp. 5–60. doi:10.1007/978-3-642-68885-0_2. ISBN978-3-642-68887-4.
Morselli, Mariafranca; Whalen, M Lynn (1996). "Appendix 2: Maple Chemistry and Quality". In Koelling, Melvin R; Heiligmann, Randall B (eds.). North American Maple Syrup Producers Manual. Bulletin. Vol. 856. Ohio State University. Archived from the original on 29 April 2006. Retrieved 20 September 2010.