There is a group of nice articles, written by Margo. But they are in POlish (also translated by wolfin to Lithuanian, but the language still not more understandible
) Still there are nice schemes, pictures and with a help of google translate
you could get some knowledge in this area
http://www.wolfdog.org/pol/articles/778.html
http://www.wolfdog.org/pol/articles/776.html
http://www.wolfdog.org/pol/articles/768.html