>I saw an English book on śakti pīṭhas which my  late father consulted during his research on the concept.

Probably D.C. Sircar,
The śakta pīṭhas.
Motilal Banarsidass keeps it in print.

Matthew Kapstein
Directeur d'études,
Ecole Pratique des Hautes Etudes

Numata Visiting Pro
fessor of Buddhist Studies,
The University of Chicago