Jens, Joseph Lambeth published two books which were combined into one in the third and later editions. The latest reprinting was made in 1980 by a baking association so it is still covered by copyright.
I suggest that you look in the catalogues of public libraries as some have an older edition--possibly in their reserves, but still accessible for reading. You should also search ebay worldwide on a weekly basis--it is possible to buy at less than $200 from sellers who do not over-inflate prices.
There are some modern books with chapters of this technique:
Wilton Way of Cake Decorating Volume II (1977) which sells for $25 or less (plus shipping). Again just ignore the overpriced listings
Toba Garrett Professional Cake Decorating (either edition) discounted from Amazon
and of course Royal Icing by Eddie Spence OBE has all the techniques required to do work in the Lambeth style (book also discounted from Amazon). You can then simply find images of Lambeth work and reproduce them.