The unramified principal series of p-adic groups. I. The spherical function
Compositio Mathematica, Volume 40 (1980) no. 3, p. 387-406
@article{CM_1980__40_3_387_0,
     author = {Casselman, William},
     title = {The unramified principal series of $p$-adic groups. I. The spherical function},
     journal = {Compositio Mathematica},
     publisher = {Sijthoff et Noordhoff International Publishers},
     volume = {40},
     number = {3},
     year = {1980},
     pages = {387-406},
     zbl = {0472.22004},
     mrnumber = {571057},
     language = {en},
     url = {http://www.numdam.org/item/CM_1980__40_3_387_0}
}
Casselman, W. The unramified principal series of $p$-adic groups. I. The spherical function. Compositio Mathematica, Volume 40 (1980) no. 3, pp. 387-406. http://www.numdam.org/item/CM_1980__40_3_387_0/

[1] A. Borel: Admissible representations of a semi-simple group over a local field with vectors fixed under an Iwahori subgroup. Inventiones Math. 35 (1976) 233-259. | MR 444849 | Zbl 0334.22012

[2] A. Borel and J. Tits: Groupes réductifs, Publ. Math. I.H.E.S. 27 (1965) 55-151. | Numdam | MR 207712 | Zbl 0145.17402

[3] A. Borel and J. Tits: Compléments à l'article "Groupes.réductifs", Publ. Math. I.H.E.S. 41 (1972) 253-276. | Numdam | MR 315007 | Zbl 0254.14018

[4] A. Borel and J. Tits: Homomorphismes "abstraits" de groupes algebriques simples. Annals of Math. 97 (1973) 499-571. | MR 316587 | Zbl 0272.14013

[5] N. Bourbaki: Groupes et algèbres de Lie. Chapitres IV, V, et VI. Hermann, Paris, 1968. | MR 240238

[6] F. Bruhat and J. Tits: Groupes réductifs sur un corps local, Publ. Math. I.H.E.S. 41 (1972) 1-251. | Numdam | MR 327923 | Zbl 0254.14017

[7] W. Casselman: Introduction to the theory of admissible representations of p-adic reductive groups (to appear).

[8] N. Iwahori: Generalized Tits systems on p-adic semi-simple groups, in Algebraic Groups and Discontinuous Subgroups. Proc. Symp. Pure Math. IX. A.M.S., Providence, 1966. | MR 215858 | Zbl 0199.06901

[9] I.G. Macdonald: Spherical functions on a p-adic Chevalley group. Bull. Amer. Math. Soc. 74 (1968) 520-525. | MR 222089 | Zbl 0273.22012

[10] I.G. Macdonald: Spherical functions on a group of p-adic type. University of Madras, 1971. | MR 435301

[11] R. Steinberg: Lectures on Chevalley groups. Yale University Lecture Notes, 1967. | MR 466335

[12] H. Matsumoto: Analyse Harmonique dans les Système de Tits Bomologiques de Type Affine. Springer Lecture Notes#590, Berlin, 1977. | MR 579177 | Zbl 0366.22001

[13] J. Tits: Reductive groups over local fields. Proc. Symp. Pure Math. XXXIII, Amer. Math. Soc., Providence, 1978. | MR 546588 | Zbl 0415.20035