The science potential of ALFA: Adaptive optics with natural and laser guide starsR. I. Davies, W. Hackenberg, T. Ott, A. Eckart, S. Rabien, S. Anders, S. Hippler, M. Kasper, P. Kalas, A. Quirrenbach and A. GlindemannAstron. Astrophys. Suppl. Ser., 138 2 (1999) 345-353DOI: https://doi.org/10.1051/aas:1999278