Costantino, Alexander. The Cimbasso and Tuba in the Operatic Works of Giuseppe Verdi: A Pedagogical and Aesthetic Comparison, dissertation, August 2010; (https://digital.library.unt.edu/ark:/67531/metadc31531/m1/1/: accessed June 26, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .