@article{225, abstract = {We revisit recent work of Heath-Brown on the average order of the quantity r(L1(x))⋯r(L4(x)), for suitable binary linear forms L1,...,L4, as x=(x1,x2) ranges over quite general regions in ℤ2. In addition to improving the error term in Heath-Browns estimate, we generalise his result to cover a wider class of linear forms.}, author = {de la Bretèche, Régis and Timothy Browning}, journal = {Compositio Mathematica}, number = {6}, pages = {1375 -- 1402}, publisher = {Cambridge University Press}, title = {{Binary linear forms as sums of two squares}}, doi = {10.1112/S0010437X08003692}, volume = {144}, year = {2008}, }