Data analysis is made by using classical oscillator fit method with preliminary data obtained from a Kramers-Kronig analysis which leads to a rapid convergence of the procedure. It has been found that the procedure can be used satisfactorily for the analysis of infrared reflection spectra of both the crystals (such as α-quartz) with separated bands, and LiNbO3 with overlapping bands having remarkably different intensities. Even those spectra with weak bands fading into strong ones can be processed satisfactorily.