We prove that for every forest F, every graph with no minor isomorphic to F has path-width at most |V(F)| -2. © 1991.
Bienstock, D., Robertson, N., Seymour, P., & Thomas, R. (1991). Quickly excluding a forest. Journal of Combinatorial Theory, Series B, 52(2), 274–283. https://doi.org/10.1016/0095-8956(91)90068-U