TY  - RPRT
TI  - The soiling characteristics of structural masonry units : report
AU  - Cullen, William C
AU  - Walton, William W
PY  - 1961
PB  - National Bureau of Standards
CY  - Gaithersburg, MD
SN  - NBS RPT 7065
DO  - 10.6028/NBS.RPT.7065
ER  -