[1] Calderbank, D. M. J., Diemer, T.: 
Differential invariants and curved Bernstein–Gelfand–Gelfand sequences. J. Reine Angew. Math. 537 (2001), 67–103. 
MR 1856258 | 
Zbl 0985.58002[2] Cap, A., Gover, A. R, Hammerl, M.: Projective BGG equations, algebraic sets, and compactifications of Einstein geometries. arXiv:1005.2246, May 2010.
[3] Čap, A., Slovák, J.: 
Parabolic geometries. I. Math. Surveys Monogr., American Mathematical Society, 2009. 
MR 2532439 | 
Zbl 1183.53002[5] Davidson, M. G., Enright, T. J., Stanke, R. J.: 
Differential operators and highest weight representations. Mem. Amer. Math. Soc. 94 (455) (1991), iv+102. 
MR 1081660 | 
Zbl 0759.22015[6] Enright, T., Howe, R., Wallach, N.: 
A classification of unitary highest weight modules. Representation theory of reductive groups (Park City, Utah, 1982), Birkhäuser Boston, 1983. 
MR 0733809 | 
Zbl 0535.22012[7] Enright, T. J.: 
Analogues of Kostant’s $\mathfrak{u}$–cohomology formulas for unitary highest weight modules. 392 (1988), 27–36. 
MR 0965055[12] Pandžič, P.: 
Dirac operators on Weil representations II. Math. Commun. 15 (2) (2010), 411–424. 
MR 2814264 | 
Zbl 1207.22009[13] Vogan, D. A., Jr., : 
Unitary representations and complex analysis. Representation theory and complex analysis, Lecture Notes in Math., vol. 1931, Springer, Berlin, 2008, pp. 259–344. 
MR 2409701 | 
Zbl 1143.22002