TY - RPRT TI - Letter Circular 663: specifications for the manufacture and installation of motor truck, built-in, self-contained, and portable scales (supersedes Letter Circular 152) PY - 1941 PB - National Institute of Standards and Technology CY - Gaithersburg, MD SN - LCIRC 663 DO - 10.6028/NBS.LCIRC.663 ER -