@article{stenger:1966:ebab,
    author = {Stenger, Frank},
     title = {Error bounds for asymptotic solutions of differential
              equations. {I}{I}. {T}he general case},
   journal = {J. Res. Nat. Bur. Standards Sect. B},
    volume = {70B},
      year = {1966},
     pages = {187–210},
   mrclass = {34.50},
  mrnumber = {MR0219824 (36 \#2902)},
mrreviewer = {F. W. J. Olver},
     zblno = {0233.65049}}