Christensen JE, Horner Jr HT, Lersten NR (1972). "Pollen wall and tapetal orbicular wall development in Sorghum bicolor (Gramineae)". American Journal of Botany. 59 (1): 43–58. doi:10.2307/2441229. JSTOR2441229.
Christensen JE, Horner Jr HT, Lersten NR (1972). "Pollen wall and tapetal orbicular wall development in Sorghum bicolor (Gramineae)". American Journal of Botany. 59 (1): 43–58. doi:10.2307/2441229. JSTOR2441229.