Here is the booklist for Chapter 1 of the study guide. Foster offers these as "an excellent background and framework out of which to study the Christian Disciplines." He does not mean that you have to read them all right away or at all. If you wish, choose one to read through slowly.
As I have said before, do not expect checklists for perfection. The authors were products of their times. This does not mean that they were stupid or ignorant, but they swam in the currents of their lives, and a fish may not know that it is wet. You are doing the same thing right now. Have grace for them and for yourself, and learn from them.
The Imitation of Christ (orig. De Imitatione Christi) by Thomas à Kempis (Thomas van Kempen) (1380-1471) "Undisputed leader of the classics of Christian devotion."
Introduction to the Devout Life (orig. Introduction à la vie dévote) by Francis (François) de Sales (1567-1622) "For those seeking to deepen their devotional life."
The Practice of the Presence of God (orig. Maximes spirituelles fort utiles aux âmes pieuses, pour acquérir la présence de Dieu) by Brother Lawrence (Laurent de la Résurrection) (1614-1691) "These simple letters and conversations...have inspired three centuries of Christians to life in more intimate communion with Christ."
The Sacrament of the Present Moment (orig. L'Abandon à la divine providence) by Jean Pierre de Caussade (1675-1751) "Sheer delight to read."
A Serious Call to a Devout and Holy Life by William Law (1686-1761) "An influential work on the Christian life."
Christian Perfection (orig. Instructions et Avis sur Divers Points de la Morale et de la Perfection Chrétienne) by François Fénelon (1695-1715) "Letters of spiritual counsel and direction on a multιtude of practical matters."
Discipline and Discovery by Albert Edward Day (1884-1973) "Practical wisdom for us all."
A Testament of Devotion by Thomas Raymond Kelly (1893-1941) "I can count on one hand the twentieth-century classics of devotion--this is one of them."
The Pursuit of God by A.W. Tozier (1897-1963) "A tender sensitive book filled with insight and a catholicity of outlook that is refreshing."
The Healing Light by Agnes Sanford (1897-1982) "A book which has influenced my own pilgrimage immensely."
The Normal Christian Life (正常的基督徒生活) by Watchman Nee (Ni Tuosheng) (1903-1972) "An important statement on the Christian life which stands in counter-distinction to so much of 'normal Christianity.'"
The Cost of Discipleship (orig. Nachfolge) by Dietrich Bonhoeffer (1906-1945) "The book that gave us the term 'cheap grace' and so forcefully called us to a more costly form of discipleship."
The Disciplined Life by Richard Shelley Taylor (1912-2006) "A sharp, staccato plea for disciplined living in an age of self indulgence."
Journey Inward, Journey Outward by Elizabeth O'Connor (active mid-20th ct.) "Sets forth in life situations the twin disciplines of the inward journey of devotion and the outward journey of service."
Christian Disciplines: Meditations for Prayer Classes by Harold Wiley Freer (active mid-20th ct.) "Short meditations that evince an unusual awareness of the Devotional Classics."
Freedom from Sinful Thoughts: Christ Alone Breaks the Curse (orig. Freiheit von Gedankensünden: Nur Christus bricht den Fluch) by Heini Arnold (1913-1982) "An insightful little book on inner thought-life."
Making All Things New by Henri Nouwen (1932-1996) "A small but powerful invitation to the spiritual life."
A Long Obedience in the Same Direction by Eugene H. Peterson (1932-2018) "Helps Christians wrestle with many of the classical Spiritual Disciplines."
As I have said before, do not expect checklists for perfection. The authors were products of their times. This does not mean that they were stupid or ignorant, but they swam in the currents of their lives, and a fish may not know that it is wet. You are doing the same thing right now. Have grace for them and for yourself, and learn from them.
The Imitation of Christ (orig. De Imitatione Christi) by Thomas à Kempis (Thomas van Kempen) (1380-1471) "Undisputed leader of the classics of Christian devotion."
Introduction to the Devout Life (orig. Introduction à la vie dévote) by Francis (François) de Sales (1567-1622) "For those seeking to deepen their devotional life."
The Practice of the Presence of God (orig. Maximes spirituelles fort utiles aux âmes pieuses, pour acquérir la présence de Dieu) by Brother Lawrence (Laurent de la Résurrection) (1614-1691) "These simple letters and conversations...have inspired three centuries of Christians to life in more intimate communion with Christ."
The Sacrament of the Present Moment (orig. L'Abandon à la divine providence) by Jean Pierre de Caussade (1675-1751) "Sheer delight to read."
A Serious Call to a Devout and Holy Life by William Law (1686-1761) "An influential work on the Christian life."
Christian Perfection (orig. Instructions et Avis sur Divers Points de la Morale et de la Perfection Chrétienne) by François Fénelon (1695-1715) "Letters of spiritual counsel and direction on a multιtude of practical matters."
Discipline and Discovery by Albert Edward Day (1884-1973) "Practical wisdom for us all."
A Testament of Devotion by Thomas Raymond Kelly (1893-1941) "I can count on one hand the twentieth-century classics of devotion--this is one of them."
The Pursuit of God by A.W. Tozier (1897-1963) "A tender sensitive book filled with insight and a catholicity of outlook that is refreshing."
The Healing Light by Agnes Sanford (1897-1982) "A book which has influenced my own pilgrimage immensely."
The Normal Christian Life (正常的基督徒生活) by Watchman Nee (Ni Tuosheng) (1903-1972) "An important statement on the Christian life which stands in counter-distinction to so much of 'normal Christianity.'"
The Cost of Discipleship (orig. Nachfolge) by Dietrich Bonhoeffer (1906-1945) "The book that gave us the term 'cheap grace' and so forcefully called us to a more costly form of discipleship."
The Disciplined Life by Richard Shelley Taylor (1912-2006) "A sharp, staccato plea for disciplined living in an age of self indulgence."
Journey Inward, Journey Outward by Elizabeth O'Connor (active mid-20th ct.) "Sets forth in life situations the twin disciplines of the inward journey of devotion and the outward journey of service."
Christian Disciplines: Meditations for Prayer Classes by Harold Wiley Freer (active mid-20th ct.) "Short meditations that evince an unusual awareness of the Devotional Classics."
Freedom from Sinful Thoughts: Christ Alone Breaks the Curse (orig. Freiheit von Gedankensünden: Nur Christus bricht den Fluch) by Heini Arnold (1913-1982) "An insightful little book on inner thought-life."
Making All Things New by Henri Nouwen (1932-1996) "A small but powerful invitation to the spiritual life."
A Long Obedience in the Same Direction by Eugene H. Peterson (1932-2018) "Helps Christians wrestle with many of the classical Spiritual Disciplines."