It is and has been out of print for a while so all copies are probably gone unless you can find a used one, I dont know if or when it will be updated and re-printed, no immediate plans for it.
Martin Koch has a book called build your electric guitar or something like that that has a little information in it.
My book dealt with manipulating the materials, no big secrets just mostly working with the wire, building pickup bobbins and putting it all together, all the basic mechanical stuff.
It was really meant to have Guitar Electronics for musicians along side of it which deals with why pickups work and gives alot of examples of different manufacturers product. I didnt want to re-write that book but it had nothing in it about how to actually make a pickup.
I wouldnt let not having the book stop you, there really are no big secrets, if you spend the time doing it youll figure it out, much like guitar playing, the more time you spend winding- and more importantly experiment- the more you see how deep you can go and how complex it can get.