Endoscopic groups and packets of non-tempered representations Jeffrey Adams, Joseph F. Johnson (1987) Compositio Mathematica
Erratum : “ C - ∞ -Whittaker vectors for complex semisimple Lie groups, wave front sets, and Goldie rank polynomial representations” Hisayosi Matumoto (1990) Annales scientifiques de l'École Normale Supérieure
Extensions Between Generalized Verma Modules: The Hermitian Symmetric Cases. Brad Shelton (1988) Mathematische Zeitschrift