A list of further reading on the subject of the human soul is available here.
The Writings of Bahá’u’lláh
The Hidden Words of Bahá’u’lláh
View on Bahá’í Reference Library »Prayers and Meditations by Bahá’u’lláh
View on Bahá’í Reference Library »The Seven Valleys and the Four Valleys
View on Bahá’í Reference Library »Gleanings from the Writings of Bahá’u’lláh
View on Bahá’í Reference Library »The Writings and Talks of ‘Abdu’l-Bahá
Selections from the Writings of ‘Abdu’l-Bahá
View on Bahá’í Reference Library »Paris Talks
View on Bahá’í Reference Library »The Promulgation of Universal Peace
View on Bahá’í Reference Library »Some Answered Questions
Compiled by Laura Clifford Barney.
View on Bahá’í Reference Library »Collections from the Bahá’í Writings
Bahá’u’lláh’s Teachings on Spiritual Reality
Compiled by Paul Lample. Riviera Beach, FL: Palabra Publications, 1996.
The Divine Art of Living: Selections from the Writings of Bahá’u’lláh and ‘Abdu’l-Bahá
Compiled by Mabel Hyde Payne. Wilmette, IL: Bahá’í Publishing Trust, Revised 1986.
Fire and Gold: Benefitting from Life’s Tests
Compiled by Brian Kurzius. Oxford: George Ronald Publisher, 1995.
Commentaries
Creative Dimensions of Suffering
A. M. Ghadirian. Wilmette, IL: Bahá’í Publishing, 2009.
The Purpose of Physical Reality
John S. Hatcher. Wilmette, IL: Bahá’í Publishing, 2005.
Understanding Death: The Most Important Event in your Life
John S. Hatcher. Wilmette, IL: Bahá’í Publishing, 2009.
The Odyssey of the Soul
Artemus Lamb. Oxford: George Ronald Publisher, 2003.