Authenticity: A Biblical Theology of Discernment by Thomas Dubay, S.M. (Ignatius)
Thy Will be Done: Letters to Persons in the World by St. Francis de Sales (Sophia)
Finding God's Will for You by St. Francis de Sales (Sophia)
To get me started, I wanted to learn a little more about St. Francis de Sales.
Here is a bio from Lives of the Saints With Reflections for Every Day in the Year compiled from The Lives of the Saints by Rev. Alban Butler, Benziger Brothers, 1894
Francis was born of noble and pious parents, near Annecy, 1566, and studied with brilliant success at Paris and Padua. On his return from Italy he gave up the grand career which is father had marked out for him in the service of the state, and became a priest. When the Duke of Savoy had resolved to restore the Church in the Chablais, Francis offered himself for the work, and set out on foot with his Bible and breviary and one companion, his cousin Louis of Sales. It was a work of toil, privation, and danger. Every door and every heart was closed against him. He was rejected with insult and threatened with death. But nothing could daunt or resist him, and ere long the Church burst forth into a second spring. It is stated that he converted 72,000 Calvinists. He was then compelled by the Pope to become Coadjutor Bishop of Geneva, and succeeded to the see in 1602. At times the exceeding gentleness with which he received heretics and sinners almost scandalized his friends, and one of them said to him, "Francis of Sales will go to Paradise, of course; but I am not so sure of the Bishop of Geneva: I am almost afraid his gentleness will play him a shrewd turn." "Ah," said the Saint, "I would rather account to God for too great gentleness than for too great severity. Is not God all love? God the Father is the Father of mercy; God the Son is a Lamb; God the Holy Ghost is a Dove - that is, gentleness itself. And are you wiser than God?" In union with St. Jane Frances of Chantal he founded at Annecy the Order of the Visitation, which soon spread over Europe. Though poor, he refused provisions and dignities, and even the great see of Paris. He died at Avignon, 1622.
He was canonized in 1665 and was proclaimed Doctor of the Universal Church by Pope Pius IX, in 1877
Bio from a different edition of Butler's Lives of the Saints
Patron Saints Index: Saint Francis de Sales