From BiblePortal Wikipedia

Fausset's Bible Dictionary [1]

DARA or Darda  1 Chronicles 2:6;  1 Kings 4:31. One of the four men noted for wisdom, but excelled by Solomon ( 1 Kings 4:31), sons of Zerach, of Pharez' distinguished family of Judah. (See Calcol ). "Sons of Mahol" probably mean "sons of the choir," i.e. the famous musicians of whom Ethan and Heman are named in the titles of Psalm 88 and Psalm 89. As "son" is often used for descendant, even if Mahol is a proper name their being called "sons of Mahol" in 1 Kings 4, but "sons of Zerah" in  1 Chronicles 2:6, is no objection to their identity.

Smith's Bible Dictionary [2]

Da'ra.  1 Chronicles 2:6. See Darda .

Holman Bible Dictionary [3]

 1 Chronicles 2:6  1 Kings 4:31Darda

Morrish Bible Dictionary [4]

Son or descendant of Zerah.  1 Chronicles 2:6 . In some Hebrew MSS DARDA is read. Doubtless the same as DARDA.

Hastings' Dictionary of the Bible [5]

DARA (  1 Chronicles 2:6 ). See Darda.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [6]

(Heb. Daroa', דָּרִע ; Sept. Δαρά v. r. Δαράδ , Δαραδέ ), a contracted or corrupt form ( 1 Chronicles 2:6) of the name DARDA (See Darda) (q.v.).