@article{NSJOM_2012_42_2a_12,
     author = {Farkhanda Afzal, and Qamar Afzal, and M Aslam Malik},
     title = {Modular group action on quadratic field
 by linear congruence},
     journal = {Novi Sad Journal of Mathematics},
     pages = {133-143},
     publisher = {mathdoc},
     volume = {42},
     number = {2},
     year = {2012},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_2012_42_2a_12/}
}