Pignatari, M., Zinner, E., Hoppe, P., J. Jordan, C., K. Gibson, B., Trappitsch, R., Herwig, F., Fryer, C., Hirschi, R., X. Timmes, F., "Carbon-rich presolar grains from massive stars : subsolar ¹²C/¹³C and ¹⁴N/¹⁵N ratios and the mystery of ¹⁵N", Astrophysical journal letters, 2015