I am trying to work on extending various methods to study square-free values of polynomials (or more generally, $k$-free values) over general rings of integers, and a literature review has yielded only one article that seems to address this problem: a 1993 Journal of Number Theory paper by Gouvea, linked here: http://www.sciencedirect.com/science/article/pii/S0022314X83710127#

Are there any other papers or results in the 22 years since that studies this problem?