Burns, Catherine M. "Walter Annenberg." In Immigrant Entrepreneurship: German-American Business Biographies, 1720 to the Present, vol. 5, edited by R. Daniel Wadhwani. German Historical Institute. Last modified January 07, 2015.
Which ones? Other than what the NYT reported? ("...at the credentialing ceremony, seen by millions as part of the British television program on the royal family, Mr. Annenberg used what the British press called “preposterous circumlocutions.” )
"A Lasting Legacy". University of Pennsylvania Almanac. 49 (7). Philadelphia: University of Pennsylvania. October 8, 2002. Retrieved November 24, 2007.