Hare Krishna,
The following books are recommended by Our Math
Madhurya Kadambini
Saranagati
Kalyana Kalpa Taru
Gitavali
Gitamala
Parthana Prem Bhakti Chandrika
Jaiva Dharma
Bhakti Sandharba
Bhagavat Sandharba
Tattva Sandharba
Gopal Champu
Krishna Samhita
Hari Bol!