- Mauro Garavello, Benedetto Piccoli, “Hybrid Necessary Principle”, SIAM J. Control Optim., 43, no. 5, 2005,
1867 
- G. Stefani, 2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601), 2004,
450 - Francesca Carlotta Chittaro, Gianna Stefani, 52nd IEEE Conference on Decision and Control, 2013,
1798 - Francesca Chittaro, Gianna Stefani, “Minimum-time strong optimality of a singular arc: The multi-input non involutive case”, ESAIM: COCV, 22, no. 3, 2016,
786