@article{CM_1968__19_2_95_0,
     author = {Mahler, K.},
     title = {Perfect systems},
     journal = {Compositio Mathematica},
     pages = {95--166},
     publisher = {P. Noordhoff N. V., Groningen},
     volume = {19},
     number = {2},
     year = {1968},
     mrnumber = {239099},
     zbl = {0168.31303},
     language = {en},
     url = {http://www.numdam.org/item/CM_1968__19_2_95_0/}
}