Ben-Amram, A. M.; Petersen, H. (2002). 《Improved bounds for functions related to busy beavers》. 《Theory of Computing Systems》 35. 1–11쪽. doi:10.1007/s00224-001-1052-0. MR1879169.
Adam Yedidia and Scott Aaronson (May 2016). A Relatively Small Turing Machine Whose Behavior Is Independent of Set Theory (Technical Report). MIT. arXiv:1605.04343. Bibcode:2016arXiv160504343Y.
Tristan Stérin and Damien Woods (July 2021). On the hardness of knowing busy beaver values BB(15) and BB(5,4) (Technical Report). Maynooth University. arXiv:2107.12475.
Ord, Toby (2024). “Bounds on the rates of growth and convergence of all physical processes”. arXiv:2410.10928 [physics.hist-ph].더 이상 지원되지 않는 변수를 사용함 (도움말)
Lin, Shen; Rado, Tibor (April 1965). 《Computer studies of Turing machine problems.》. 《Journal of the ACM》 12. 196–212쪽. doi:10.1145/321264.321270. S2CID17789208.
Ben-Amram, A. M.; Petersen, H. (2002). 《Improved bounds for functions related to busy beavers》. 《Theory of Computing Systems》 35. 1–11쪽. doi:10.1007/s00224-001-1052-0. MR1879169.
Adam Yedidia and Scott Aaronson (May 2016). A Relatively Small Turing Machine Whose Behavior Is Independent of Set Theory (Technical Report). MIT. arXiv:1605.04343. Bibcode:2016arXiv160504343Y.
Lin, Shen; Rado, Tibor (April 1965). 《Computer studies of Turing machine problems.》. 《Journal of the ACM》 12. 196–212쪽. doi:10.1145/321264.321270. S2CID17789208.