@article{ZNSL_2011_387_a5,
     author = {I. N. Parasidis and P. C. Tsekrekos and T. G. Lokkas},
     title = {Correct and self-adjoint problems for biquadratic operators},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {145--162},
     publisher = {mathdoc},
     volume = {387},
     year = {2011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2011_387_a5/}
}