In the first part of discourse series on Veda Mahimai, Svami has mentioned about Pradhana Shatakam and about the commentary that Svami has written in the Kanchi Perarulalan magazine. Where are these available? E-book versions are also acceptable.

Pradhana Shatakam is one of the Rahasya-s. It is found in “Chillarai Rahasyangal”. This book is available at Srirangam Srimad Poundarikapuram Ashramam.
Kanchi Perarulalan magazine is available in their office at Taramani (Hayagriva Vidyapeetham, Taramani).