ZASLAVSKY, I. D.; KHACHATRYAN, M. H. On the Comparative Complexity of Primitive Recursive Arithmetical and String Functions. Mathematical Problems of Computer Science, [S. l.], v. 39, p. 81–87, 2021. Disponível em: https://mpcs.sci.am/index.php/mpcs/article/view/424. Acesso em: 3 apr. 2025.