New York, 6 May 1955 - Institutional correspondence A letter from W.R. Keating & Company International to R. Lerondelle
New York, 23 January 1957 - Transport documents A letter from the vice-president of W. R. Keating & Company to Willem Sandberg
<em>The New York Times</em>, New York, June 13, 1971, 1 - Article “Vietnam Archive: Pentagon Study Traces 3 Decades of Growing U.S. Involvement”