In addition to making medals, the sisters contributed illustrations to books listed below. Examples of the Casella Sister's work are in the collection of the V&A.
Literature:
Dreams, Dances and Disappointments by Gertrude A. Konstam and illustrated by N Casella and E Casella. Published by Thos. de la Rue & Co, London, 1881.
The Maypole by Gertrude A. Konstam and illustrated by N Casella and E Casella. Published by Thos. de la Rue & Co, London, 1882.
The baby's "début" by J. Smith and illustrated by N Casella and E Casella. Published by Thos. de la Rue & Co, London, 1883.
With thanks to artbiogs.co.uk