581.973 Liv D Livingston, Burton Edward, 1875- The distribution of vegetation in the United States, as related to climatic conditions (by) Burton E. Livingston and Forrest Shreve. (Washington) Carnegie Institution of Washington, 1921 590 p. mapas (2 colors. plegs.) tablas. 25 cm. (Carnegie Institution of Washington. Publication, nº 284) Incluye bibliografía