This primary source comes from the Collection RN-WHPO: White House Photo Office Collection (Nixon Administration).
National Archives Identifier:
6721928Full Citation: Photograph WHPO-0941-03; North and South Exterior of White House with Tulips and Fountains Visible; 5/1/1969; Nixon White House Photographs, 1/20/1969 - 8/9/1974; Collection RN-WHPO: White House Photo Office Collection (Nixon Administration); Richard Nixon Library, Yorba Linda, CA. [Online Version, https://www.docsteach.org/documents/document/white-house-tulips, March 29, 2024]