@article{10_4064_ap_27_2_163_165,
     author = {J. W. Heidel},
     title = {Addenda to {"Periodic} solutions of $x" + f(x)x'^{2n} + g(x) = 0$ with arbitrarily large period''},
     journal = {Annales Polonici Mathematici},
     pages = {163--165},
     publisher = {mathdoc},
     volume = {27},
     number = {2},
     year = {1972},
     doi = {10.4064/ap-27-2-163-165},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-27-2-163-165/}
}