no. 1

A trace formula for reductive groups. II : applications of a truncation operator
Compositio Mathematica, Tome 40 (1980) no. 1, pp. 87-121. 
@article{CM_1980__40_1_87_0,
     author = {Arthur, James},
     title = {A trace formula for reductive groups. II : applications of a truncation operator},
     journal = {Compositio Mathematica},
     pages = {87--121},
     publisher = {Sijthoff et Noordhoff International Publishers},
     volume = {40},
     number = {1},
     year = {1980},
     zbl = {0499.10033},
     mrnumber = {558260},
     language = {en},
     url = {http://www.numdam.org/item/CM_1980__40_1_87_0/}
}
Arthur, James. A trace formula for reductive groups. II : applications of a truncation operator. Compositio Mathematica, Tome 40 (1980) no. 1, pp. 87-121. http://www.numdam.org/item/CM_1980__40_1_87_0/

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