Optical spectroscopy of the CSP-I SE SN sample. Each spectrum has been normalized to its mean flux values and plotted in units of f_λ. For presentation purposes additive constants have also been applied. The phase of each spectrum relative to the epoch of the B-band maximum is provided next to each spectrum and the spectroscopic subtype is provided below the SN designation at the top right. Vertical dashed blue lines indicate rest wavelengths of He I λλ4472, 5876, 6678, 7065, 7281 lines, vertical dashed red lines are Hγ, H β, and Hα, and the vertical gray line indicates the location of a prominent telluric feature.