Henze, M., Pietsch, W., Haberl, F., Sala, G., Quimby, R., Hernanz, M., Della Valle, M., Milne, P., Williams, G. G., Burwitz, V., Greiner, J., Stiele, H., Hartmann, D. H., Kong, A. K. H., & Hornoch, K. (2009). The first two transient supersoft X-ray sources in M 31 globular clusters and the connection to classical novae. Astronomy & Astrophysics, 500(2), 769-779. doi:10.1051/0004-6361/200811122.