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Until 1957, records were only sold in the mono format. Between 1957 and 1968 you could find records in both mono and stereo formats. In the mid-1970s, some records were available in 4 channel quadraphonic sound. Since typically not as many quadraphonic copies were made, they are usually worth more than mono or stereo versions. Worth noting is that some lateral cut monophonic vinyl 78s were made up through the mid 1950s.