TY  - SER
AU  -  Multhauf, Robert P., 
TI  -  Development of Gravity Pendulums in the 19th Century : :  
AV  - Q 
PY  - 2011///
PB  -  Project Gutenberg, 
KW  -  Pendulum
N1  -  Public domain in the USA;  Text
UR  -  http://www.gutenberg.org/ebooks/35024
ER  -