1. Benson Farb, R. Keith Dennis, Noncommutative Algebra, in Graduate Texts in Mathematics, Vol. 144 (Springer Science & Business Media, 2012)
2. Alain Connes, Michael R. Douglas, Albert Schwarz, JHEP 02, 003 (1998)
3. M. Artin, J.J. Zhang, Adv. Math. 109, 228 (1994)
4. Yuri I. Manin, Quantum Groups and Non-commutative Geometry (CRM, Montreal, 1988)
5. Yuri I. Manin, Topics in Noncommutative Geometry (Princeton, 1991)