@article{10_37236_3020,
     author = {L\'aszl\'o Sz\'ekely and Hua Wang},
     title = {Extremal values of ratios: distance problems vs. subtree problems in trees},
     journal = {The electronic journal of combinatorics},
     year = {2013},
     volume = {20},
     number = {1},
     doi = {10.37236/3020},
     zbl = {1266.05012},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/3020/}
}