@article{sips:1965:ra,
    author = {Sips, Robert},
     title = {Repr\'esentation asymptotique de la solution g\'en\'erale de
              l'\'equation de {M}athieu-{H}ill},
   journal = {Acad. Roy. Belg. Bull. Cl. Sci. (5)},
    volume = {51},
      year = {1965},
    number = {11},
     pages = {1415–1446},
     zblno = {0142.32401}}