参考文献
Andrzej Mostwski, An undecidable arithmetical statement, Fundamenta Mathematicae 36 (1), 1949, 143-164
Andrzej Mostwski, Yoshindo Suzuki, On $\omega$-models which are not $\beta$-models, Fundamenta Mathematicae 58 (1), 1969, 83-93
新井敏康, 数学基礎論, 岩波書店, 2011