MLA

Kissinger, Henry, 1923-2023. Positions on issues,1968: Hubert Humphrey, Robert F. Kennedy, Eugene McCarthy, Richard M. Nixon, Ronald Reagan [4 of 4]. Box 229, folder 4. 1968 May-July. https://collections.library.yale.edu/catalog/11786236.

APA, 6th edition

Kissinger, Henry, 1923-2023. (["Box 229, folder 4"])(1968 May-July)[Positions on issues,1968: Hubert Humphrey, Robert F. Kennedy, Eugene McCarthy, Richard M. Nixon, Ronald Reagan [4 of 4]]. https://collections.library.yale.edu/catalog/11786236.