Bromwich, Thomas John I'Anson (1926). An introduction to the theory of infinite series. American Mathematical Society Chelsea Publishing. ISBN978-0-8284-0335-1. Here is the publisher's description
Jeffreys, Harold (1929). "Bromwich's Work on Operational Methods". Journal of the London Mathematical Society. 3 (3): 220–223. doi:10.1112/jlms/s1-5.3.220.