TY  - RPRT
TI  - Letter Circular 824: structural clay products, stone, and masonry (supersedes Letter Circular 643)
PY  - 1946
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 824
DO  - 10.6028/NBS.LCIRC.824
ER  -