@article{PismaZhETF.97.260,
    title = {Topological invariants for  fractional quantum Hall states},
    author = {Gurarie, V. and Essin, A. M.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {97},
    issue = {4},
    pages = {260},
    year = {2013},
    doi = {10.7868/S0370274X13040139},
    url = {http://jetpletters.ru/ps/dx/10.7868/S0370274X13040139},
}