Many independent scholars and digital libraries have legally preserved out-of-print or scanned public domain versions of Gita Press books on the Internet Archive. Srimad Bhagavad Gita

You can download several Bengali books from Gita Press, Gorakhpur

For direct PDF downloads of major Bengali texts published by Gita Press, the hosts several high-quality scans: Srimad Bhagavad Gita (Bengali)