Richard Dedekind (1901). 〈The Nature and Meaning of Numbers, II. Transformation of a System, §§21, 25〉 (영어). Wooster Woodruff Beman 옮김. 《Essays on the Theory of Numbers》(PDF). Open Court.
MIT OpenCourseWare (2019). “Lecture Note 18: Non-Computable Functions”(PDF) (영어). 《24.118 Paradox and Infinity》. Massachusetts Institute of Technology. 1, 3쪽. 2026년 9월 30일에 확인함.
Andrew Cooper. “Domains and Rules” (영어). 《Foundations of Mathematics》. North Carolina State University. 2026년 9월 30일에 확인함. “Restrictions and Extensions”.
Andrew Cooper. “Operations on Functions” (영어). 《Foundations of Mathematics》. North Carolina State University. 2026년 9월 30일에 확인함. “Set Operations on Functions”, “The Pasting Lemma”.
Michael Greenberg (2020). “Day 25: Set Theoretic Relations and Functions” (영어). 《CS054 Discrete Mathematics and Functional Programming》. Pomona College. 2026년 9월 30일에 확인함. “Partial functions”.
J. J. O'Connor; E. F. Robertson (2005년 10월). “The function concept” (영어). 《MacTutor History of Mathematics》. University of St Andrews. 2026년 9월 30일에 확인함.