TY - JOUR AB - 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. AU - de la Bretèche, Régis AU - Timothy Browning ID - 225 IS - 6 JF - Compositio Mathematica TI - Binary linear forms as sums of two squares VL - 144 ER -