Study of single top production at high energy electron positron colliders J. Fuster, I. García, P. Gomis, M. Perelló, E. Ros and M. Vos Eur. Phys. J. C, 75 5 (2015) 223 Published online: 22 May 2015 DOI: 10.1140/epjc/s10052-015-3453-2