Harvard reference list for citing disjoint passages from the same text
How do I cite disjoint passages from the same text without implying that I have used everything between them?


In the reference list, write:

Kline, M. (1972). Mathematical Thought from Ancient to Modern Times. New York: 
Oxford University Press.


I.e., omit page numbers. In the main body, write (Kline, M. 1972, p. 50) and (Kline, M. 1972, p. 83), as you already have. In some disciplines, you can also write (Kline, M. 1972, p. 50) followed by (ibid, p. 50), when no other citations appear inbetween.