@article{VMUMM_2009_2_a4,
     author = {K. I. Oblakov},
     title = {Non-existence of distinct codirected locally minimal trees on a plane},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {21--25},
     year = {2009},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_2009_2_a4/}
}