Hi. Is there anybody here who knows more about the subject? I have two framed sketches and they have been with me for about 12 years now. I don't know what they are worth and I am trying to sell them. I searched on the internet before and came across some which are very identical to what I have, even the series number e.g. 13 of 500. Just curious as to why it would have the same series number if it is of limited prints? Thank you.