The following 6 books by Allan Kardec are the foundation of Spiritism.

The Spirits’ Book
It was Kardec’s first book and was published in 1857. It contains the principles of the Spiritist Teachings on the immortality of the soul; the nature of Spirits and their relationship with the corporeal world; the moral laws; the present life, the future life and the destiny of the human race.

The Mediums’ Book
A discussion of the means of communicating with the Spirit world and the safe development of mediumship. It shows, explains and teaches the experimental and investigative features of the Teachings.

The Gospel according to Spiritism
The Gospel contains the explanation for the moral maxims of Christ, their concordance with Spiritism and their application in various circumstances of life.

Heaven and Hell
It contains a comparative examination of the various aspects concerning the passage from the earthly life to spirit life, future rewards and punishments, angels and devils. Followed by numerous examples of the state of the soul during and after death.

Miracles and Predictions according to Spiritism. It reconciles science and religion and develops a series of important scientific and philosophical topics, relating them to Spiritism.

What is Spiritism
This book is a brief introduction to Spiritism written by Allan Kardec in 1859, about a quarter of the length of The Spirits’ Book.