@article{SMJ2_1996_22_2_a2,
     author = {Markov, Yavor},
     title = {Limit {Cycles} of {Perturbations} of a {Class} of {Quadratic} {Hamiltonian} {Vector} {Fields}},
     journal = {Serdica Mathematical Journal},
     pages = {91--108},
     publisher = {mathdoc},
     volume = {22},
     number = {2},
     year = {1996},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SMJ2_1996_22_2_a2/}
}