From BiblePortal Wikipedia

Fausset's Bible Dictionary [1]

( Genesis 12:8;  Genesis 13:3) equates to Ai, with the Hebrew article Ha , which always accompanies Ai.

Morrish Bible Dictionary [2]

The same as Ai, the translators having apparently included the article (ha) as part of the name in  Genesis 12:8; Gen.13:3, but in these passages only.

Holman Bible Dictionary [3]

 Genesis 12:8 Genesis 13:3Ai

Smith's Bible Dictionary [4]

Ha'i. Same As Ai .

International Standard Bible Encyclopedia [5]

hā´ı̄ ( העי , - ‛ay , "the heap"):   Genesis 12:8;  Genesis 13:3 the King James Version; the Revised Version (British and American) Ai (which see).