- Marlis von Hessert,
- Francis Ames-Lewis,
- Roger J. Crum,
- Mary Bonn,
- R. W. Lightbown,
- Anabel Thomas,
- Janet Southorn,
- Thomas Hirthe,
- Warren Hearnden,
- Nigel Gauk-Roger,
- Elena Fumagalli,
- Silva Mascalchi,
- Malcolm Campbell,
- Edward L. Goldberg,
- Maria Letizia Strocchi
- , and Stefano Casciu
Updated in this version
updated bibliography, 16 September 2010; updated and revised, 31 March 2000