1. "The Problem of the Safe Use of Coal-mining Explosives." W. Payman. Midland Institute of Mining Engineers, General Meeting, Leeds, April 17, 1928.
2. A full description of the method is given in "The Pressure Wave Sent Out by an Explosive," Part 1, by W. Payman and H. Robinson. Part 2 by W. Payman and W. Shepherd. Safety in Mines Research Board Papers, No. 18 and No. 29.