@article{10_4064_cm_26_1_157_163,
     author = {K. Radziszewski},
     title = {\ensuremath{\pi}-geodesics and lines of shadow},
     journal = {Colloquium Mathematicum},
     pages = {157--163},
     publisher = {mathdoc},
     volume = {26},
     number = {1},
     year = {1972},
     doi = {10.4064/cm-26-1-157-163},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-26-1-157-163/}
}