Antti Hannukainen Sergey Korotov Tomás Vejchodský On Weakening Conditions for Discrete Maximum Principles for Linear Finite Element Schemes. 297-304 2008 NAA http://dx.doi.org/10.1007/978-3-642-00464-3_32 conf/naa/2008 db/conf/naa/naa2008.html#HannukainenKV08