@techreport {popa09,
	title = {On a general extending and constraining procedure for linear iterative methods},
	year = {2009},
	month = {August},
	institution = {IWR, University of Heidelberg},
	type = {Technical Report},
	url = {http://www.ub.uni-heidelberg.de/archiv/9761},
	author = {Nicola, A. and Petra, S. and Popa, C. and Schn{\"o}rr, C.}
}
