Achak, A., R. . Daher, and N. Safouane. “Titchmarsh Theorems and K-Functionals for the Two-Sided Quaternion Fourier Transform”. International Journal of Engineering and Applied Physics, vol. 1, no. 1, Jan. 2021, pp. 26-37, https://ijeap.org/ijeap/article/view/2.