Our Greek database is based on
Mounce, William D. Basics of Biblical Greek Grammar. 2d ed. Grand Rapids: Zondervan, 2003.
Frequency is in the process of being updated to reflect:
Trenchard, Warren C. The Complete Vocabulary Guide to the Greek New Testament. Rev ed. Grand Rapids: Zondervan, 1998.
Our Hebrew database is based on
Van Pelt, Miles V., and Gary D. Pratico. The Vocabulary Guide to Biblical Hebrew. Grand Rapids: Zondervan, 2003.
Pratico, Gary D., and Miles V. Van Pelt, Basics of Biblical Hebrew. 2d ed. Grand Rapids: Zondervan, 2009.