Archival newspapers are also a rich source... and I discovered some treasure trove of photos of exteriors and signage of older Chinese restaurants... but not many of interiors or of people at work in their kitchens or dining rooms.
I discovered lots of interesting info about Chinese cafes all over the world, especially in the U. K., but decided I can't go to far afield, and will stick with U. S. and Canada to keep the project manageable. Besides, the stories are pretty similar for all the Chinese in the restaurant business no matter which country they settled in.