1. A. Antonevich and A. Lebedev, Functional Differential Equations, I: C*-Theory (Longman, Harlow, 1994).
2. V. E. Nazaikinskii, A. Yu. Savin, and B. Yu. Sternin, Elliptic Theory and Noncommutative Geometry (Birkhäuser, Basel, 2008).
3. P. Baum and A. Connes, A Fête of Topology (Academic, Boston, Mass., 1988).
4. G. Luke, J. Differ. Equations 12, 566–589 (1972).
5. M. F. Atiyah and I. M. Singer, Ann. Math. 87, 484–530 (1968).