Ruy, V. De Moraes, M.O.C. Brasil Sobrinho, and E. Malavolta. 1987. “ Contribution to the Study of Available Boron Soils of the State of S. Paulo, Brazil: I . Growth and Mineral Composition of Sunflower (Helianthus Annus Mill.) ”. Anais Da Escola Superior De Agricultura Luiz De Queiroz 44 (1): 695-739. https://doi.org/10.1590/S0071-12761987000100037.