Bharat Adsul Madhavan Mukund K. Narayan Kumar Vasumathi Narayanan Causal Closure for MSC Languages. 335-347 2005 conf/fsttcs/2005 FSTTCS http://dx.doi.org/10.1007/11590156_27 db/conf/fsttcs/fsttcs2005.html#AdsulMKN05