Lea, I. (1867). Index to Vol. I. to XI. of Observations on the Genus
Unio, Together with Description of New Species of the Family Unionidæ. And Descriptions of New Species of the Melanidæ, Paludinæ, Helicidæ, etc. Read before the American Philosophical Society and the Academy of Natural Sciences of Philadelphia, and Published in their Journal, from 1827 to 1863. 63 pp. [with errata and corrigenda section on pp. 61–62]. Printed for the author, Philadelphia.