@article{ZNSL_1977_67_a4,
     author = {P. P. Tammela},
     title = {Minkowski reduction region for positive quadratic forms in seven variables},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {108--143},
     publisher = {mathdoc},
     volume = {67},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1977_67_a4/}
}