I received a message from someone at Hand & Lock, an embroidery firm in England. Their website is most interesting. I had no idea that an entire firm would be devoted to embroidery!
They recommended this book as the best reference for hand embroidery. It was published in 1884! I guess this is a case of their being nothing new under the sun.
I did purchase a book from Amazon. I will share it with you as soon as it arrives.