TY  - JOUR
T1  - A Simple Apparatus for Approximate Harmonic Analysis and for Periodicity Measurements
JF  - Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character (1905-1934)
VL  - 99
IS  - 699
SP  - 283
EP  - 292
PY  - 1921/07/01/
UR  - http://dx.doi.org/10.1098/rspa.1921.0043
M3  - doi:10.1098/rspa.1921.0043
AU  - Balls, W.
ER  -