Eschenroeder, Erin; Sarah Mills; Thao Nguyen (30 September 2006). William Frawley (ed.). The Expression of Modality. The Expression of Cognitive Categories. Mouton de Gruyter. pp. 8–9. ISBN978-3-11-018436-5. Retrieved 3 January 2010.
Ruth C. Barcan (March 1946). "A Functional Calculus of First Order Based on Strict Implication". Journal of Symbolic Logic. 11 (1): 1–16. doi:10.2307/2269159. JSTOR2269159. S2CID250349611.
Ruth C. Barcan (December 1946). "The Deduction Theorem in a Functional Calculus of First Order Based on Strict Implication". Journal of Symbolic Logic. 11 (4): 115–118. doi:10.2307/2268309. JSTOR2268309. S2CID31880455.
Ruth C. Barcan (March 1947). "The Identity of Individuals in a Strict Functional Calculus of Second Order". Journal of Symbolic Logic. 12 (1): 12–15. doi:10.2307/2267171. JSTOR2267171. S2CID43450340.
McKinsey, J. C. C. (1941). "A Solution of the Decision Problem for the Lewis Systems S2 and S4, with an Application to Topology". J. Symb. Log. 6 (4): 117–134. doi:10.2307/2267105. JSTOR2267105. S2CID3241516.
Adams, Robert M. Theories of Actuality. Noûs, Vol. 8, No. 3 (Sep., 1974), particularly pp. 225–31.
Ruth C. Barcan (March 1946). "A Functional Calculus of First Order Based on Strict Implication". Journal of Symbolic Logic. 11 (1): 1–16. doi:10.2307/2269159. JSTOR2269159. S2CID250349611.
Ruth C. Barcan (December 1946). "The Deduction Theorem in a Functional Calculus of First Order Based on Strict Implication". Journal of Symbolic Logic. 11 (4): 115–118. doi:10.2307/2268309. JSTOR2268309. S2CID31880455.
Ruth C. Barcan (March 1947). "The Identity of Individuals in a Strict Functional Calculus of Second Order". Journal of Symbolic Logic. 12 (1): 12–15. doi:10.2307/2267171. JSTOR2267171. S2CID43450340.
McKinsey, J. C. C. (1941). "A Solution of the Decision Problem for the Lewis Systems S2 and S4, with an Application to Topology". J. Symb. Log. 6 (4): 117–134. doi:10.2307/2267105. JSTOR2267105. S2CID3241516.
Ruth C. Barcan (March 1946). "A Functional Calculus of First Order Based on Strict Implication". Journal of Symbolic Logic. 11 (1): 1–16. doi:10.2307/2269159. JSTOR2269159. S2CID250349611.
Ruth C. Barcan (December 1946). "The Deduction Theorem in a Functional Calculus of First Order Based on Strict Implication". Journal of Symbolic Logic. 11 (4): 115–118. doi:10.2307/2268309. JSTOR2268309. S2CID31880455.
Ruth C. Barcan (March 1947). "The Identity of Individuals in a Strict Functional Calculus of Second Order". Journal of Symbolic Logic. 12 (1): 12–15. doi:10.2307/2267171. JSTOR2267171. S2CID43450340.
McKinsey, J. C. C. (1941). "A Solution of the Decision Problem for the Lewis Systems S2 and S4, with an Application to Topology". J. Symb. Log. 6 (4): 117–134. doi:10.2307/2267105. JSTOR2267105. S2CID3241516.
Andrew H. Miller, "Lives Unled in Realist Fiction", Representations 98, Spring 2007, The Regents of the University of California, ISSN0734-6018, pp. 118–134.