Really, there is no Xilinx or Altera book. Most of what you need to know is more aimed at synthesis languages like VHDL or Verilog, with an emphasis on how that gets translated into just about any FPGA family. Altera or Xilinx makes almost no real impact on what you code in the HDL. There are some differences in I/O features available, and at least with Xilinx, they have a bunch of different families that have different I/O features. So, look more closely at books about designing with HDLs, and then get the specific info on internal architecture and I/O features from the respective company's datasheets.
At least, Xilinx tells you a LOT about internal architecture (which really is not of much use, you just let the synthesis tools deal with that) and the I/O architecture, which you do need to understand what can be done in the I/O blocks easily.
Jon