41 books
Observations on the Genus Unio, Together with Descriptions of New Genera and Species (V6 18)
Observations on the Genus Unio, Together with Descriptions of New Genera and Species (Volume 2)
Observations on the Genus Unio, Together with Descriptions of New Genera and Species (V 1)
Observations on the Genus Unio, Together with Descriptions of New Genera and Species (Volume 5)