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https://books.google.it/books?id=hZi3Eky4X7kC&pg=PA16&lpg=PA16&dq=Finch,+R.H.,+1937,+A+tree+ring+calendar+for+dating+volcanic+events+at+Cinder+Cone,+Lassen+Volcanic+National+Park,+California:+American+Journal+of+Scie&source=bl&ots=YjKcE0DQ2Y&sig=ACfU3U0u4MhLIy2nAxXCBz3qxP0NIOihXw&hl=it&sa=X&ved=2ahUKEwjG2pHL8KroAhVAy8QBHV_KDH8Q6AEwAXoECAoQAQ#v=onepage&q=Finch%2C%20R.H.%2C%201937%2C%20A%20tree%20ring%20calendar%20for%20dating%20volcanic%20events%20at%20Cinder%20Cone%2C%20Lassen%20Volcanic%20National%20Park%2C%20California%3A%20American%20Journal%20of%20Scie&f=false