Shepherd, Marc. "Introduction: Historical Context", The Grand Duke (piano score), p. xxvii, New York: Oakapple Press, 2009. Linked at "The Grand Duke", The Gilbert and Sullivan Archive
"Charles H Workman", AHRC Research Centre for the History and Analysis of Recorded Music, accessed 1 February 2022; and Shepherd, Marc. "C. H. Workman's Gilbert and Sullivan", Gilbert and Sullivan Discography, accessed 1 February 2022
"Charles H Workman", AHRC Research Centre for the History and Analysis of Recorded Music, accessed 1 February 2022; and Shepherd, Marc. "C. H. Workman's Gilbert and Sullivan", Gilbert and Sullivan Discography, accessed 1 February 2022