TY - JOUR AU - Cong Qin AU - Xinfu Chen AU - Xin Lai AU - Wanghui Yu TI - Regularity of free boundary arising from optimal exercise of perpetual executive stock options JO - Interfaces and free boundaries PY - 2015 SP - 69 EP - 92 VL - 17 IS - 1 UR - http://geodesic.mathdoc.fr/articles/10.4171/ifb/334/ DO - 10.4171/ifb/334 ID - 10_4171_ifb_334 ER -