Panama Canal traffic, capacity, and tolls : hearing before the Subcommittee on Panama Canal of the Committee on Merchant Marine and Fisheries, House of Representatives, Ninety-first Congress, second session on a report from the Panama Canal Company officials on a projection of the canal traffic, capacity, and tolls as they affect the Panama Canal and on a report on the impact of the IMCO universal measurement tonnage system on the Panama Canal tonnage assessment system, April 22, 1970