Signed Dietrich Grunewald Floral Serigraph

Hello Everyone,
Finding some really interesting items at our local Goodwill lately ! Today's find is my signed Dietrich Grunewald Serigraph.
It is one of his large florals. It's done in blues, grays, yellows, and greens . It's framed in a pale green and white painted wood frame with the canvas floating in the middle. It has the Van Amstel tag # C-1154 but no title that I could find. The bio sheet is there, but the serigraph definition one is torn off except for the "What is a serigraph" glued on the stretcher. The stretcher has 36" x 42" -25 written on it in pencil. It is in excellent condition. No rips tears or dents. Just a bit of dust. I still need to find out the canvas's date, title and value. He worked for the Van Amstel Co. for 20 years starting in 1956 creating these serigraphs for high-end furniture stores,much like Robert Lawson. So this canvas could be somewhere between 1956-1976 I'm thinking the 1960's. I've seen some online that range from $100.00 to 1000.00 or more. He's a fairly well known and very accomplished artist. He died in 2003 and his son posted a really good bio and video online at http://dietrichart.com/. -Mike- :)