Hi all
I read that (Spane and Wurstner (1993) )presented an alternative method for computing derivatives. Like the Bourdet method.
Do u have any information about this?? OR ANY PAPERS THAT ILLUSTRATE THIS TOPIC.

I ALSO NEED THIS PAPER IF AVALIABLE::
Spane, F.A., Jr., and S.K. Wurstner, 1993. DERIV: A computer program for calculating pressure derivatives for use in hydraulic test analysis, Ground Water, vol. 31, no. 5, pp. 814-822