an Huef, Astrid, Marcelo Laca, and Iain Raeburn. “Boundary Quotients of the Right Toeplitz Algebra of the Affine Semigroup over the Natural Numbers”. New Zealand Journal of Mathematics 52 (September 19, 2021): 109–143. Accessed April 23, 2024. https://nzjmath.org/index.php/NZJMATH/article/view/90.