Most of the books written by Swami Satyananda Saraswati can be found in Bengali only. But there are some available in english.
Path to Evolution
This magnum opus of Swamiji deals with the evolution of human consciousness. Translation of the first part of this book can be found here.
A Powerful Commentary on Politics
A discourse on application of powerful thoughts in politics - a translation is available here.
This book deals with the traces of Ancient Vedic civilization pervasive all over the world. This book (partially in Bengali) can be downloaded.
This is a translation of the original text in Bengali.
How the state and society should be reformed based on principles of Shaktivada? You can find it in this book.
His other works in Bengali include,
Shaktishali Samaj (Empowering Society)
Dharmashiksha (A Primer on Dharma)
Anandamather Siddhasadhak (The Sage from the Tradition of Anandamath : An autobiography)
Shaktivada Bhashya Gita ( Shaktivada Commentary on Gita)
Shaktivada Bhashya Upanishad ( Shaktivada Commentary on Upanishad)