OK many thanks, it should be d / dt on the RHS of Eq. (6).
Sent: 08/03/2017 01:51:07 GMT Standard Time
Subj: Full Spanish version of UFT 371
Please find enclosed the Full Spanish version (3 sections) of UFT 371, for posting.
By the way, we found a typo on Eq.(6) of the English version of this paper, which should probably get fixed.