RTL Hardware Design Using VHDL
Other suggested textbooks:
Synthesizable VHDL Design for FPGAs
FPGA Prototyping by VHDL Examples
For people who care about clean code:
Effective Coding with VHDL: Principles and Best Practice
The book's accompanying material has a coding style guide that you can get from the link below (included in the zip file), which nicely summarizes the proper style discipline introduced in the book:
Search avaliable e-resources at Lund University Library.