Lace, William W. The Medieval Cathedral. Lucent Books, 2001.
The book is shown twice because these pages contain information on arches and their construction.
The pages shown below have information on architects.
Even if you use both resources, the book is only listed once in the Works Cited page since it's the same book.
Lace, William W. The Medieval Cathedral. Lucent Books, 2001.
Macaulay, David. Cathedral: The Story of Its Construction. Houghton
Mifflin, 1973.