TY  - JOUR 
T1  - Studies of semiquinone free radicals by ESR in the whole soil, HA, FA and humin substances
JO  - Journal of the Brazilian Chemical Society
A1  - Saab, Sérgio C
A1  - Martin-Neto, Ladislau
SN  - 0103-5053
UL  - 10.1590/S0103-50532004000100007
VL  - 15 
Y1  - 2004
PB  - Brasil 
ER  -