@article{CMH_1978__53_139723,
     author = {Wilfred Kaplan},
     title = {On the trajectories of a quadratic differential, {I.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {57--72},
     year = {1978},
     volume = {53},
     zbl = {0382.30030},
     url = {http://geodesic.mathdoc.fr/item/CMH_1978__53_139723/}
}