RT Journal Article SR Electronic T1 World-Power and Evolution JF Science JO Science FD American Association for the Advancement of Science SP 211 OP 213 DO 10.1126/science.50.1287.211-a VO 50 IS 1287 A1 Schuchert, Charles YR 1919 UL http://science.sciencemag.org/content/50/1287/211.2.abstract AB