@article{ZNSL_2012_403_a3,
     author = {M. Karev},
     title = {Covers counting via {Feynman} calculus},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {58--80},
     publisher = {mathdoc},
     volume = {403},
     year = {2012},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2012_403_a3/}
}