Michael Lynch is a PhD student at Calvin Theological Seminary, and he is doing pioneer work on Hypothetical Universalism. While the term itself has been in more or less common currency, the actual theologians and primary sources which espouse the view have not. Mr. Lynch is seeking to push beyond the 2nd and 3rd-hand commentary and present the original sources, including the original definitions and state of the question. You can listen to his recent lecture for the Junius Institute on this topic here.