BIOLOGICAL NITROGEN  FIXATION--EARLY AMERICAN STYLE (SAMUEL W. JOHNSON AND WILBUR O. ATWATER).
D000383:Agriculture; D005006:Ethnicity; D049672:History, 19th Century; D049673:History, 20th Century; D000455:Medicago sativa; D008511:Medicine; D009586:Nitrogen Fixation; D014481:United States
AGRICULTURE; ALFALFA; BIOGRAPHIES; HISTORY; HISTORY OF MEDICINE, 19TH CENT.; NITROGEN FIXATION; UNITED STATES