“…m 2 c 2 f (x, y, t), u (5) = f (x cos ε − y sin ε, y cos ε + x sin ε, t), u (6) = f (x cosh cε − tc sinh cε, y, t cosh cε − (x/c) sinh cε), u (7) = f (x, y cosh cε − tc sinh cε, t cosh cε − (y/c) sinh ε), u (α) = f (x, y, t) + εα(x, y, t) where ε is any real number and α(x, y, t) is any other solution to two dimensional KG equation for a free particle with mass m. At the end the most general solution that we can obtain from a given solution u = f (x, y, t), by group transformations is in the form given below…”