There are three really good books on Ernie Kovacs. They are:
The MT&R published a companion book in conjunction with its huge Kovacs exhibition 1986, and that's available at the Museum's gift shop. The book contains a complete TV videography as well as some well-written, loving critical essays of Ernie's work.
And, of course there is the novel Ernie wrote, Zoomar.
I acquired a hardcover copy through a used book place (Gryphon Books) in
New York. There's also the book Ernie wrote called How to Talk at
Gin. Some libraries may have either of these on their shelves (if
some fan hasn't permanently borrowed it). If you're library doesn't have
them, you can borrow them via inter-library loan. And of course,
eBay is the best place to find copies of these as well as of the many issues
of MAD Magazine Ernie contributed to.