Yes! I have that (Domestic Geese/Ashton) book! I highly recommend it. I spent one whole winter delving into Euro sites looking for pics of Sebs. I was just curious as to what they considered to be a good example. I went into sites in Germany, France, Great Britain, Italy and others. I think I got into Spain, also. These sites were poultry shows and clubs. Don't speak enough of any of the languages to have been able to really read the descriptions, but saw a lot of cool pics! I bookmarked them, but they have almost all vanished off the internet. I should have printed them out! I saw lots of smooth breasted and almost smooths, and the curlies appeared lighter overall with a flatter forehead than ours in the USA. I'll have to try some more Euro surfing in the future.
Also, the parents of the curly grays I've got are a smooth and a smooth breasted. The gander is from Holderreads. I must add my Holderreads ganders are colors. I'd also like to add that so far the colored geese I have develop very slowly. Most have been over a year old before they maxed out on there feathering, then they do not improve after that.
I thought just a few curled or long scapular feathers indicated a smooth. The goose I own that I've been calling smooth gets long scapular feathers in the summer.