Springer, the publisher, has made a large number of their books free. Of particular interest (in PDF and Epub formats):

Introduction to Logic Circuits & Logic Design with VHDL by Brock J. LaMeres, 2017
Introduction to Logic Circuits & Logic Design with Verilog by Brock J. LaMeres, 2017

Possibly also of interest:
Electronics for Embedded Systems by Ahmet Bindal, 2017

These are worthwhile references to have around, even for the hobbyist. Dr. LaMeres writes in a clear and unpretentious style, which definitely eases the task of absorbing the content of his books. Good find, Ed.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

They are great books. I also found the second edition of the same books:
https://link.springer.com/book/10.1007% ... 30-13605-5
https://link.springer.com/book/10.1007% ... 30-12489-2

And you have quick start guides to both verilog and VHDL:
https://link.springer.com/book/10.1007% ... 30-10552-5
https://link.springer.com/book/10.1007% ... 30-04516-6

Here is a long list of many books that are free:
https://www.thebiomics.com/notes/spring ... -list.html

Knowledge is power...

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!