They are many other derivative and/or integral methods adapted to flow period or flow regime identification. Some of these include
Argawal
The derivative of pressure/pressure difference with respect to he logarithm of Agarwal time.
dP/dt
This is a traditional derivative of pressure/pressure difference with respect to elapsed time. In some literature, it may also be called the primary pressure derivative. The primary pressure derivative (PPD) was developed to identify wellbore effects within a pressure response, so they can be separated from reservoir effects