Original paper about the all or none law for neurons
This probably goes back to Lucas (1909), Adrian (1912), and Bernstein (1912). But the idea might have started from Helmholtz (1850).


Lucas, K (1909). The ``all or none'' contraction of the amphibian skeletal muscle fibre. Journal of Physiology; 38: 113--133.
Adrian, ED (1912). On the conduction of subnormal disturbances in normal nerve. Journal of Physiology; 45: 389--412
Bernstein, J (1912). Electrobiologie. Braunschweig: Vieweg.


See also: Galvani's Spark: The Story of the Nerve Impulse and The great Era of English Electrophysiology:
from Francis Gotch to Hodgkin and Huxley