1. Appel, A. W. (1998). SSA is functional programming. ACM SIGPLAN Notices, 33(4):17–20.
2. Appel, K. and Haken, W. (1976). Every planar map is four colorable. Bull. Amer. Math. Soc., 82:711–712.
3. Barras, B., Boutin, S., Cornes, C., Courant, J., Coscoy, Y., Delahaye, D., de Rauglaudre, D., Filliâtre, J.-C., Giménez, E., Herbelin, H., et al. (1999). The Coq proof assistant reference manual. INRIA, version, 6(11).
4. Bertot, Y. and Castéran, P. (2013). Interactive Theorem Proving and Program Development: Coq’Art: The Calculus of Inductive Constructions. Springer Science & Business Media.
5. Gonthier, G. (2008). Formal proof–the four-color theorem. Notices of the AMS, 55(11):1382–1393.