Bab. No year - Babington CC (1838) IV. Descriptions of those species of Polygonum and Fagopyrum which are contained in the Indian Herbarium of J. Forbes Royle, Esq., F.L.S., &c., late Superintendant of the H.E.I. Botanical Garden at Saharunpore, and now Professor of Materia Medica in K. Transactions of the Linnean Society of London 18(1): 93-119. doi: 10.1111/j.1095-8339.1838.tb00165.x.
There is no corrections for Polygonum roylei yet.