TY  - RPRT
TI  - Economics of protection against progressive collapse 
AU  - Chapman, Robert E
AU  - Colwell, Peter F
PY  - 1974
PB  - National Bureau of Standards
CY  - Gaithersburg, MD
SN  - NBS IR 74-542
DO  - 10.6028/NBS.IR.74-542
ER  -