1. ^{{Cite book|url=https://books.google.co.uk/books?id=eDUEAAAAMBAJ&pg=PA59&lpg=PA59&dq=dr+joseph+kler&source=bl&ots=KGnQPjKxbh&sig=ACfU3U2hbIlEDE8ibcm7T_AA6CfsuLiXmA&hl=en&sa=X&ved=2ahUKEwi7_PC32bjgAhUMnhQKHQcJCzUQ6AEwBHoECAQQAQ#v=onepage&q=dr%20joseph%20kler&f=false|title=The Rotarian |author=Rotary International |date=1971|publisher=Rotary International|year=|isbn=|location=|pages=59|language=en}}
2. ^{{Cite book|url=https://books.google.co.uk/books?id=TEIEAAAAMBAJ&pg=PA62&dq=known+for+collected+medical+stamps&hl=en&sa=X&ved=0ahUKEwjC9caQ2bjgAhVZSRUIHRobCMwQ6AEILTAB#v=onepage&q=kler&f=false|title=The Rotarian |author=Rotary International |date=1958|publisher=Rotary International|year=|isbn=|location=|pages=62|language=en}}
3. ^{{Cite news|url=https://www.nytimes.com/1983/11/25/obituaries/joseph-h-kler-80-physician-andpreservationistinjersey.html|title=Joseph H. Kler, 80, Physician AndPreservationistinJersey|last=|first=|date=1983-11-25|work=The New York Times|access-date=22 February 2019|language=en-US|issn=0362-4331}}
4. ^{{Cite web|url=https://www.libraries.rutgers.edu/history_of_medicine/manuscripts/kler|title=Joseph H. Kler, MD (1903-1983) - Papers, 1935 - 1980, w/gaps {{!}} Rutgers University Libraries|last=|first=|date=|website=www.libraries.rutgers.edu|archive-url=|archive-date=|dead-url=|access-date=22 February 2019}}