Duncan amber art glass vase

This was a find from yesterday. It is 7.5" tall, made with a four part mold. Not sure how to describe this pattern, so not sure how to search for it. I did make a stab at it, though. Very well made, super quality, but the mold lines on the top of the base were not removed. Kind of a shallow vase but very pretty. Pretty certain it is American art glass. Lots of bubbles in this one. Looks like I am collecting glass again. Since I can't get at my reference books, I am going to buy some new ones, so welcome recommendations on titles. If I can find them used and cheap, I will buy them.