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.
This is a weighty, comprehensive, and modern book on crystallography. If you are going to buy anything, this is what I would recommend.
Elements of X-Ray Diffraction, 3rd Edition (2014), B.D. Cullity and S.R. Stock. Pearson.
This is a general x-ray diffraction text that is more oriented to materials studies than most. Commonly used as a teaching textbook. Despite the publication date, it was last revised in 2001, I believe.
International Tables for Crystallography Volume C: Mathematical, Physical and
Chemical Tables, (2021) T. R. Welberry ed.
DOI: 10.1107/97809553602060000117
This is a comprehensive and pricey reference on all types of diffraction, with tables and articles on practically everything, but is probably much more than you want. Your library/institution may have arranged on-line access, even if they don’t have a print copy.
Origin and application of the Lorentz factor in X-ray diffraction (2026), Gasser, F., Simbrunner, J., Freychet, G., Demitri, N., Holy, V., and Resel, R. Acta Crystallographica Section A, 82(5), 350-360. https://doi.org/doi:10.1107/S2053273326005917
The Lorentz correction is discussed at depth and re-derived in this recent open access Acta Cryst. A article.