Phillips, M. M.Simon, Joshua D.Morrell, NBurns, ChristopherKarakas, AmandaPatat, FerdinandoHsiao, E YContreras, CSuntzeff, NPenprase, B EPerley, DanielPignata, G.Campillay, A2015-12-130004-637Xhttp://hdl.handle.net/1885/75735High-dispersion observations of the Na I D λλ5890, 5896 and K I λλ7665, 7699 interstellar lines, and the diffuse interstellar band at 5780 Å in the spectra of 32 Type Ia supernovae are used as an independent means of probing dust extinction. We showOn the source of the dust extinction in type Ia supernovae and the discovery of anomalously strong Na i absorption201310.1088/0004-637X/779/1/382015-12-11