Fundamentals of Powder Diffraction and Structural Characterization of Materials (2025), P. Y. Zavalij and V. K. Pecharsky. Springer, DOI: 10.1007/978-3-031-91504-8
There is a short chapter on Fourier techniques and some discussion of Pawley and Le Bail extraction here.
Fundamentals of Crystallography. Third Edition (2011). C. Giacovazzo, H. L. Monaco, G. Artioli, D. Viterbo, M. Milaneso, G. Ferraris, G. Gilli, P. Gilli, G. Zanotti and M. Catti. Edited by C. Giacovazzo. IUCr Texts on Crystallography No. 15, IUCr/Oxford University Press.
There is some discussion of Fourier techniques here.
The Fast Fourier Transform (1974), E. O. Brigham, Prentice-Hall.
As a graduate student, I found this book very helpful for understanding Fourier transforms. The next two URLs may be even more valuable.