TY  - BOOK
AU  - Unknown
TI  - Measuring Tools Machinery's Reference Series Number 21
PY  - 2013///
PB  - Project Gutenberg
N1  - Project Gutenberg; Freely available; Electronic text
UR  - http://www.gutenberg.org/etext/43375
UR  - http://www.gutenberg.org/license
ER  -