The book you may have seen is called "the helicopter pilot's handbook"
by Phil Croucher , i have a copy and have started reading it in combination with my ATPL studies and so far its quite good, it covers the 206 well, worth a read.
Chester
Just noticed that the same author has a book that elaborates on the chapter about 206's for sale called "the bell 206 book" i'll have to order one!