TY  - JOUR 
T1  - Origin and nature of humic substances in the waters of the Amazon River Basin
JO  - Acta Amazonica
A1  - Leenheer, Jerry A.
SN  - 0044-5967
UL  - 10.1590/1809-43921980103513
VL  - 10 
Y1  - 1980
PB  - Brazil 
ER  -