Ahmed, Mamoon, and Fida Moh’d. 2018. “THE HECKE ALGEBRA \(H(P_{\mathbb{Q}}, P_{\mathbb{Z}})\) AND ITS RELATION TO THE CROSSED PRODUCT \(H(P_{\mathbb{Q}}^{+}, P_{\mathbb{Z}})\) \(\times_{β}\) {1, −1}”. Italian Journal of Pure and Applied Mathematics 39 (February):569-78. https://journals.uniurb.it/index.php/ijpam/article/view/6882.