1. Stochastically curtailed tests in long-term clinical trials;Lan;Sequent. Anal.,1982
2. A unified theory for sequential clinical trials;Whitehead;Stat. Med.,1999
3. Sequential monitoring of clinical trials: the role of information and Brownian motion;Lan;Stat. Med.,1993
4. Sequential methods based on the boundaries approach for the clinical comparison of survival times;Whitehead;Stat. Med.,1994