@article{BASM_2008_1_a3,
     author = {Dana Schlomiuk and Nicolae Vulpe},
     title = {Integrals and phase portraits of planar quadratic differential systems with invariant lines of total multiplicity four},
     journal = {Buletinul Academiei de \c{S}tiin\c{t}e a Republicii Moldova. Matematica},
     pages = {27--83},
     publisher = {mathdoc},
     number = {1},
     year = {2008},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/BASM_2008_1_a3/}
}