Mantra Book Better Upd: Shivyog Durga Saptashati Beej

It's important to distinguish that some sources refer to an Amazon customer review mentioning a "Shri Durga Saptasati and Shrimad Bhagvad Gita" book as a best book for bhakti that is concise and complete with well-written mantras. However, this is a general devotional book , not the specialized beej mantra sadhana book we are focusing on.