Venerable Nyanaponika A. Thera
The four sublime states
Heart of Buddhist Meditation
The Vision of Dhamma
Anguttara Nikaya: Pt. 2
Heart of Buddhist Meditation: A Handbook of Mental Training Based on the Buddha's Way of Mindfulness
Roots of Good and Evil
The Four Sublime States: AND the Practice of Loving Kindness - Metta
The Heart of Buddhist Meditation