 In the next approximation (i.e., with account to small γ"a"3 and derivatives by "x", "y"), they determine the quantities γ"a"3 by already known γ33 and γ"ab".Contraction of gives formula_143, and, hence,
Different cases are possible depending on the "G" variable.In the above case "g"00 = γ33 formula_67 γ"ab" and formula_145.