Clemens Zeidler Christof Lutteroth Wolfgang Stuerzlinger Gerald Weber Evaluating Direct Manipulation Operations for Constraint-Based Layout. 513-529 2013 INTERACT (2) https://doi.org/10.1007/978-3-642-40480-1_35 conf/interact/2013-2 db/conf/interact/interact2013-2.html#ZeidlerLSW13