@article{article3ca2333c,
title   = {Comparison of isotope techniques and non-nodulating isolines to study the effect of ammonium fertilization on dinitrogen fixation in soybean, Glycine max},
author = {Ruschel, Alaides Puppin and Vose, Peter B and Victoria, Reynaldo Luiz and Salati, Eneas},
year = {1979},
doi = {10.1007/bf02140722},
journal   = {Plant and Soil}
}