GRIFFOR, E. R. Definability and forcing in E-recursion. Mathematica Scandinavica, Berkeley, CA, United States, v. 57, p. 5–28, 1985. DOI: 10.7146/math.scand.a-12103. Disponível em: https://journals.msp.org/mscand/article/view/1564. Acesso em: 25 jul. 2026.