Even with modern painters there are many works in important public and private collections already established, which should not be there. The great success of the Chinese art market recently and the indifferent use of reproductions of paintings everywhere especially the internet, bears great risks when we try to establish valid references for painters even still alive.
So while we have not enough or no references for older artworks, we have often too many references for modern paintings.
What does make a known painting a reference? Could we trust big collections, museums?
In general everybody faces the same problems here. The team of experts in a big auction house or museum has to find the same answers as a private collector and therefore it would be rather easy to point out the one or the other mistake in the evaluation of a painting.
When of course a museum in China has a painting of a modern painter it should be easily accepted. But on a song painting also the collection seals of the Qing imperial collection are not really any guarantee for authenticity. Already in the Qing dynasty the situation is as bad as it is today and maybe now with the better exchange of data we are able to form a better picture for certain painters than a couple of hundred years earlier.

So is already a general acceptance of references difficult, a more differentiated view on lifetime of the artist, painted subject etc. should be desired too.
We will understand the value of references when we discuss the categories of quality and authentication better.

Now we should establish an order for the categories of quality.

In the very important first place are the quality of the composition and the quality of the painting. This includes a generally appreciation of the inherent logic of the composition and its execution in calligraphic brushwork, ink shading and colouration.