Reply to the 'Comment on "A universal approach for calculating the Judd–Ofelt parameters of RE3+ in powdered phosphors and its application for the β-NaYF4:Er3+/Yb3+ phosphor derived from auto-combustion-assisted fluoridation"' by D. Zhang, Q. Xu and Y. Zhang, Phys. Chem. Chem. Phys., 2019, 21, DOI: 10.1039/C8CP07577H. Issue 20 (15th May 2019)