@article{MZM_2012_92_5_a5,
     author = {E. G. Karpuz and A. S. Cevik},
     title = {Gr\"{o}bner--Shirshov {Bases} for {Extended} modular, {Extended} {Hecke,} and {Picard} {Groups}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {699--706},
     publisher = {mathdoc},
     volume = {92},
     number = {5},
     year = {2012},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2012_92_5_a5/}
}