Hello everyone!

Is there any definitive source or authority for stroke order?

I just downloaded an app to practice writing characters, which I've found tremendously useful until I tried to write the traditional character for turtle: 龜.

As you can see, it's quite a unique character in the way that it's composed. I'd written it before but I wasn't sure if I'd done it correctly, so I tried using the app.

It came up with a bizzare stroke order that felt completely unnatural, so I searched online for answers. To confound the problem, what I found was two more different sources with two more different stroke orders. Though they seemed more logical, now I had three discrepant versions of the same character, and one of them was actually composed differently, which was even more confusing.

The legs, and the top and bottom parts of the shell were joined by the same stroke, which wasn't the case in any other source. So I checked Pleco and, again, different-looking different-composed character. Now I had three versions of the same character which all varied not only in the way the were written, but also in how the looked.

I've also seen discrepancies in the way different sources say you should write 出, 可 and others, and I'm getting confused.

I remember getting told off by my teacher when I just started learning Chinese, who was very strict about stroke order and told me very plainly I'd written a character the "wrong" way.

Now I wonder whether there is any source or authority for the standard on this. Is there even a standard at all? Is there anywhere one can check? Sorry for the long post, but thank you so much for reading!