Christoph Burnikel Rudolf Fleischer Kurt Mehlhorn Stefan Schirra A Strong and Easily Computable Separation Bound for Arithmetic Expressions Involving Radicals. 87-99 2000 27 Algorithmica 1 http://link.springer.de/link/service/journals/00453/bibs/0027001/00270087.html db/journals/algorithmica/algorithmica27.html#BurnikelFMS00