TY  - RPRT
TI  - Guide to schema and schema extensibility 
AU  - Rosen, Bruce K
AU  - des, Fontaines Isabella
PY  - 1991
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - NIST SP 500-197
DO  - 10.6028/NIST.SP.500-197
ER  -