Bartko, H., Martins, F., Fritz, T. K., Genzel, R., Levin, Y., Perets, H. B., et al. (2009). Evidence for warped disks of young stars in the galactic center. The Astrophysical Journal, 697(2), 1741-1763. doi:10.1088/0004-637X/697/2/1741.