Nguyen, Hai-Chau Max Planck Institute for the Physics of Complex Systems, Max Planck Society;
http://iopscience.iop.org/article/10.1209/0295-5075/115/10003/meta (Publisher version)
Nguyen, H.-C., & Vu, T. (2016). Necessary and sufficient condition for steerability of two-qubit states by the geometry of steering outcomes. EPL, 115: 10003. doi:10.1209/0295-5075/115/10003.