Thapar, Gobind Singh. “The Lymph Glands in the Genus Pheretima With a Note on the Coelomic Organ of Beddard”. Records of the Zoological Survey of India, vol. 15, no. 2, Aug. 1918, pp. 69-75, doi:10.26515/rzsi/v15/i2/1918/163566.