@article{oai:repository.dl.itc.u-tokyo.ac.jp:00052078,
 author = {Ifa, Abdelwaheb and Louati, Hanen and Rouleux, Michel},
 issue = {2},
 journal = {Journal of Mathematical Sciences The University of Tokyo},
 month = {Jun},
 pages = {91--127},
 title = {Bohr-Sommerfeld quantization rules revisited : The method of positive commutators},
 volume = {25},
 year = {2018}
}