Richardson, Daniel (1968). "Some Undecidable Problems Involving Elementary Functions of a Real Variable". Journal of Symbolic Logic. 33 (4): 514–520. doi:10.2307/2271358. JSTOR2271358. Zbl0175.27404.
Richardson, Daniel (1968). "Some Undecidable Problems Involving Elementary Functions of a Real Variable". Journal of Symbolic Logic. 33 (4): 514–520. doi:10.2307/2271358. JSTOR2271358. Zbl0175.27404.
Richardson, Daniel (1968). "Some Undecidable Problems Involving Elementary Functions of a Real Variable". Journal of Symbolic Logic. 33 (4): 514–520. doi:10.2307/2271358. JSTOR2271358. Zbl0175.27404.