Peter Kirschenhofer Jörg M. Thuswaldner Elements of small norm in Shanks' cubic extensions of imaginary quadratic fields. 1471-1486 2004 38 J. Symb. Comput. 6 http://dx.doi.org/10.1016/j.jsc.2004.05.005 db/journals/jsc/jsc38.html#KirschenhoferT04