Clipart Of Inside Of A Department Store Does This Have A Copyright?

Does this have a copyright? - clipart of inside of a department store

I am publishing in the second year on my own book a few months. I would like a small medieval art of good quality (which is a history of medieval fantasy), and found this site:

http://etc.usf.edu/clipart/galleries/des ...

I included eight boundaries and in the manuscript, with everything as you want. Then a friend told me that I was not able to use it! They are protected by copyright! I searched and searched for them, and I do not give it so easily. What do you think? If you have a book that would put these characters in them? I have that on the date of publication in the top 2 in my book: "Frontiers and Decorations by courtesy of © Clipart ETC