Spectroscopy Project Help

Hi, I am currently working on a spectroscopy project to measure the rotational velocities of stars for spectral classifications O, B, A, and F. My spectograph can only collect data between 5000A and 7000A. I was wondering what resources you suggest to determine the best wavelength ranges to focus my spectograph on? Should I use a solar atlas to determine this or some other data? I'm just struggling on determing exactly what wavelengths/lines would be best to focus on for this project, and ANY advice would be appreciated. Thanks!