It seems various people often have various ways to write the same characters. For instance, I have seen the radical "忄" being written in three different ways (left, middle, right; left, right, middle; and middle, left, right) which is a lot for such a small radical. Chinese teachers sometime don't even agree on what should be the correct stroke order.
So is there any authoritative source on what the correct stroke order for a character should be? Perhaps some book published by the government?