@ARTICLE {SANGINGA:1996a,
title = {Field measurements of nitrogen fixation in leguminous trees used in agroforestry systems: influence of 15N-labelling approaches and reference trees},
author = {Sanginga, N. and Danso, S. K. A. * and Zapata, F. },
journal = {Biology and Fertility of Soils},
year = {1996},
volume = {23},
pages = {26--32},
}