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author = {M. Ainsworth and A. Craig},

title = {A posteriori error 
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journal = {Numerische Mathematik},

volume = {60},

number = {},

year = {1992},

pages = {429-463}}


@article{R.A.Albanese_R.L.Medina_J.W.Penn,

author = {R.A. Albanese and R.L. Medina and J.W. Penn},

title = {Mathematics, medicine and microwaves},

journal = {Inverse Problems},

volume = {10},

number = {},

year = {1994},

pages = {995-1007}}