@book{AST_1989__169-170__1_0,
     author = {Babbitt, D. G. and Varadarajan, V. S.},
     title = {Local moduli for meromorphic differential equations},
     series = {Ast\'erisque},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {169-170},
     year = {1989},
     mrnumber = {1014083},
     zbl = {0683.34003},
     language = {en},
     url = {http://www.numdam.org/item/AST_1989__169-170__1_0/}
}