@article{700214,
     title = {Discretisation and error estimates for elliptic boundary value problems of the fourth order},
     booktitle = {Differential Equations and Their Applications},
     series = {GDML\_Books},
     publisher = {Slovensk\'e pedagogick\'e nakladate\v lstvo},
     address = {Bratislava},
     year = {1967},
     pages = {301-305},
     zbl = {0182.14301},
     url = {http://dml.mathdoc.fr/item/700214}
}

Zlámal, M. Discretisation and error estimates for elliptic boundary value problems of the fourth order, dans Differential Equations and Their Applications, GDML_Books,  (1967), pp. 301-305. http://gdmltest.u-ga.fr/item/700214/