Ó Ceallaigh, S. T., & O'Brien, W. (1919). Letter from Seán T. Ó Ceallaigh, Paris, to William O'Brien, Liberty Hall, Dublin, asking him to introduce Frank P. Walsh, Chairman of the American Commission on Irish Independence, to prominent labour workers during his visit to Dublin, and informing him he has become well acquainted with his well-travelled brother, Thomas J. O'Brien.

Ó Ceallaigh, Seán T., and William O'Brien. Letter from Seán T. Ó Ceallaigh, Paris, to William O'Brien, Liberty Hall, Dublin, Asking Him to Introduce Frank P. Walsh, Chairman of the American Commission on Irish Independence, to Prominent Labour Workers During His Visit to Dublin, and Informing Him He Has Become Well Acquainted with His Well-travelled Brother, Thomas J. O'Brien. 1919.