Not only are these two scientific works quite scarce, they are impossible to find signed! Waveguides is signed by both authors. Cavour is Yeh's first name (see other book), and Fred is Shimabukuro's first name. Numerical Electromagnetics is signed by Yeh only.

 Both books are in near pristine condition with no faults. They are clean, tight and issue free throughout. I won't comment on the content of the books as it is far too technical for me.

  Essence is published by Springer in 2008 and is a first printing. Electromagnetics is published by California Advanced Studies in 2015 and is also a first printing. A rare pair of signed first editions.