1. Exterior Differential Systems;Bryant,1991
2. Special symplectic connections;Cahen;J. Differ. Geom.,2009
3. Differential invariants and curved Bernstein–Gelfand–Gelfand sequences;Calderbank;J. Reine Angew. Math.,2001
4. Parabolic Geometries. I. Background and General Theory;Čap,2009