Shadow Letters and the Karnana Letter: Indians Negotiate the White Australia Policy, 1901–1921 Allen, Margaret.. "Shadow Letters and the Karnana Letter: Indians Negotiate the White Australia Policy, 1901–1921." Life Writing 8 (2011): 187.
Roy Vollmer’s letters Roy Vollmer’s letters In Pakcap – Correspondence to/from Roy Gus, October 8, 1964 thru June 30, 1965. Vol. Box LIK 117. Philadelphia: University of Pennsylvania and Pennsylvania Historical and Museum Commission, Louis I. Kahn Collection, 1965.
Review off target [Letter to the editors] Schaefer, P.. "Review off target [Letter to the editors]." Journal of the American Planning Association 69, no. 3 (2003): 316.
Neil Thompson, letter to Henry Wilcots, 17 October 1968 Neil Thompson, letter to Henry Wilcots, 17 October 1968 In Pac Correspondence To/Fr Gus, Jun 1968 thru Dec. 31, 1968. University of Pennsylvania and Pennsylvania Historical and Museum Commission, Kahn Collection, Box LIK 117. Philadelphia (USA), 1968.