@article {Nicola-et-al-2011,
	title = {A general extending and constraining procedure for linear iterative methods},
	journal = {Int.~J.~Comp.~Math.},
	year = {2011},
	note = {in press},
	url = {http://dx.doi.org/10.1080/00207160.2011.634002},
	author = {Nicola, A. and Stefania Petra and Popa, C. and Christoph Schn{\"o}rr}
}
@article {Nicola-et-al-2011,
	title = {A general extending and constraining procedure for linear iterative methods},
	journal = {Int. J. Comp. Math.},
	year = {2011},
	note = {in press},
	url = {http://dx.doi.org/10.1080/00207160.2011.634002},
	author = {Nicola, A. and Petra, S. and Popa, C. and Schn{\"o}rr, C.}
}
@techreport {popa09,
	title = {On a general extending and constraining procedure for linear iterative methods},
	year = {2009},
	institution = {IWR, University of Heidelberg},
	url = {http://www.ub.uni-heidelberg.de/archiv/9761},
	author = {Nicola, A. and Stefania Petra and Popa, C. and Christoph Schn{\"o}rr}
}
@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.}
}
