SAIGON'S FORCES QUIT FOURTH BASE IN LAOS FIGHTING
S Vietnamese troops evacuate another base in Laos; 60 US helicopters haul about 700 S Vietnamese soldiers out of Landing Zone Brown and surrounding jungles; N Vietnamese gunners continue to pound Saigon forces with mortar and arty fire; Col Nguyen Xuan Loc repts 2 bns left near Landing Zone Brown; about 6,000 S Vietnamese troops have been pulled back towards S Vietnamese border recently; details on action; illus; map
