Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Excellent but incomplete history of Pan American's Clippers

Cohen's book is among the better works to document the short but exciting history of Pan American's pacific clipper operations, providing insight into the pilots and aircraft that flew it and the route they took. My few complaints were with the relative dirth of information following the outbreak of World War II, some speculative accounts which have been correctly described in other books, and a lack of color photos. Still, for the price it is a most valuable addition to anyone's aviation library.