I finished a 36 x 80 Oak Entry Door with sidelights a few weeks ago - quite a
bit of work, but well worth the effort. It's one of the few projects I get to
look at several times a day!
Two books I got thorugh Amazon were "Doormaking A it Yourself Guide" by John
Birchard and "Handcrafted Doors and Windows" by Amy Zaffarono Rowland
The first gives lots pf practical advice, as well as designs for several types
of doors, while the second has some unique ideas for artistics styling.