Eugene, is instructive.
But writing in the pictures, the word "forgery" should be very cautious, it is better not to do. A charming lady told me the story several years ago:
In the early 90's in an antique shop, comrade dragged Edward Sternberg (hopefully forumcanam do not represent who he is), to show him two of his works exhibited for sale. In a rage, shouting - falshak! Edik these works are not just torn. Vendors shop begging him not to do. Then he felt-tip pen, bold, on the back written "Falshak" and signed it.
What was surprising stories of the narrator, when he had a couple of years, I saw one of the works on sale. The word "falshak" was very neatly displayed, but on the back of the picture adorned the genuine signature of the artist
