TY  - JOUR 
T1  - Critical levels and sufficiency ranges for leaf nutrient diagnosis in cowpea grown in the Northeast region of Brazil
JO  - Revista Ciência Agronômica
A1  - Melo, Francisco de Brito
A1  - Souza, Henrique Antunes de
A1  - Bastos, Edson Alves
A1  - Cardoso, Milton Jose
SN  - 1806-6690
UL  - 10.5935/1806-6690.20200071
VL  - 51 
Y1  - 2020
PB  - Brasil 
ER  -