@article{bender:1973:qo,
    author = {Bender, Carl M. and Wu, Tai Tsun},
     title = {Anharmonic oscillator. II. A study of perturbation theory
              in large order},
   journal = {Phys. Rev. D},
    volume = {7},
      year = {1973},
     pages = {1620–1636},
       doi = {10.1103/PhysRevD.7.1620}}