TY  - JOUR
T1  - On the Double Tangent of a Plane Curve. 
JF  - Proceedings of the Royal Society of London (1854-1905)
VL  - 9
SP  - 724
EP  - 725
PY  - 1857/01/01/
UR  - http://dx.doi.org/10.1098/rspl.1857.0150
M3  - doi:10.1098/rspl.1857.0150
AU  - Cayley, A.
ER  -