Cassell is a British book publishing house founded in 1848 by John Cassell (1817–1865), which became in the 1890s an international publishing group company. In 1995, Cassell plc acquired Pinter Publishers. In December 1998, Cassell plc was bought by the Orion Publishing Group. In January 2002, Cassell imprints, including the Cassell Reference and Cassell Military, were joined with the Weidenfeld imprints to form a new division under the name of Weidenfeld & Nicolson Ltd. Cassell Illustrated survives as an imprint of the Octopus Publishing Group. History.
https://en.wikipedia.org/wiki/Cassell_(publisher)