@article{shirts:1993:am,
    author = {Shirts, R. B.},
     title = {\NOOP{B}Algorithm 721: {MTIEU1} and {MTIEU2}: Two subroutines to compute
              eigenvalues and solutions to {M}athieu's differential equation for
              noninteger and integer order},
   journal = {ACM Trans. Math. Software},
    volume = {19},
      year = {1993},
    number = {3},
     pages = {391–406},
      note = {Double-precision Fortran, maximum accuracy 18D},
      issn = {0098-3500},
       doi = {10.1145/155743.155847},
     links = {\GAMSmodule{TOMS}{721}{11787}},
     zblno = {0892.65058}}