Lothal: Seal: L-48 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 249: Collections in India: Suomalainen Tiedeakatemia.
There is only one extant example of this Indus sign.
Indus Script Signs with Numbers: List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.