In addition to the hard copy of Harrison's book, you might try the paperback
"Seabirds of the World" (also Harrison) which has some helpful photos. Good
luck--I keep trying but it's an uphill struggle! The most help I've ever had
was from Kenn Kaufman"s "Advanced Birding"--that's really the best book I
could recommend to anyone -- about LOTS of I.D. problems. It's also available
from ABA.

Murray Hansen
Graham, WA
MurrayH at aol.com