Hummel is known for his essay, "Tyranny of the Urgent", published in 1967 as a booklet by
InterVarsity Press, which became popular as guide to time management and personal productivity in both ministry and business circles, and has since undergone periodic updates and revisions. In 1997 he published "Freedom from Tyranny of the Urgent", an expansion upon his original work.
During his life Hummel authored fifteen books and
Bible studies.
Selected bibliography
A Pure Heart: The Window to God
Campus Christian Witness
Creation or Evolution?: Resolving Crucial Issues
Doubters Welcome
Filled with the Spirit
Fire in the Fireplace
Freedom from Tyranny of the Urgent
Genesis: God's Creative Call
Healing
Priorities
The Galileo Connection
The Search: Studies for pondering the know-why of existence