Cosmic nitrogen, sodium, and aluminum nuclei are a combination of primaries produced at cosmic-ray sources and secondaries resulting from collisions of heavier primary cosmic rays with the interstellar medium. We present high-statistics measurements of the N, Na and Al rigidity spectra. We discuss the properties and composition of their spectra and present a model-independent determination of their primary and secondary components, together with the mostly primary cosmic rays C, Ne, Mg, and S. This allows us to determine the C/O, N/O, Ne/Si, Na/Si, Mg/Si, Al/Si, and S/Si abundance ratios at the source independently of cosmic-ray propagation models.