TY  - RPRT
TI  - Letter Circular 18 (Communication B516): important European screw thread systems and dimensions of bolt and screw heads and nuts
PY  - 1922
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 18
DO  - 10.6028/NBS.LCIRC.18
ER  -