W.B. Honey, Catalogue of the Porcelain and Pottery both Oriental and European in the Collection of Earl Spencer at Althorp, 1937, no. 657, including a transcription of a letter from Lady Sarah Spencer to her brother, Hon. R.G. Spencer, April 27th, 1809 - 'My Grandmother Lucan has just sent Mrs. Fisher two china pigeons to stand on her chimney piece; and I assure you no bronze statues or marble vases ever were half as much admired as these pigeons are.'