Richard, Bertha. "A comparative study of the digestive systems of Cambarincola philadelphica (Leidy, 1951) and Xironodrilus formosus (Ellis, 1819) (Annelida, oligochaeta, branchiobdellidae) /." Doctoral dissertation, Ohio State University, 1971. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487343760227637Chicago Manual of Style (17th edition)