Friedman WE (1998), "The evolution of double fertilization and endosperm: an "historical" perspective", Sexual Plant Reproduction, 11: 6, doi:10.1007/s004970050114, S2CID19785565
Houk WG (1938). "Endosperm and Perisperm of Coffee with Notes on the Morphology of the Ovule and Seed Development". American Journal of Botany. 25 (1): 56–61. doi:10.2307/2436631. JSTOR2436631.
Houk WG (1938). "Endosperm and Perisperm of Coffee with Notes on the Morphology of the Ovule and Seed Development". American Journal of Botany. 25 (1): 56–61. doi:10.2307/2436631. JSTOR2436631.
Friedman WE (1998), "The evolution of double fertilization and endosperm: an "historical" perspective", Sexual Plant Reproduction, 11: 6, doi:10.1007/s004970050114, S2CID19785565