@article{MABA_2000_14_3-4_a11,
     author = {P. G. Todorov},
     title = {A {Representation} of a {Nonnegative} {Algebraic} {Polynomial} of {Degree} {Four} as a {Sum} of {Two} {Squares} of {Real} {Polynomials}},
     journal = {Mathematica balkanica},
     pages = {305},
     publisher = {mathdoc},
     volume = {14},
     number = {3-4},
     year = {2000},
     url = {http://geodesic.mathdoc.fr/item/MABA_2000_14_3-4_a11/}
}