That´s not an absolute truth. The name was kept on some markets all the time, but they were not badged Amazon after 1958 as far as I know. The name Amazon was protected by Kreidler on some markets, so Volvo had to use 121/122S instead. The numbers were on the cars on all markets, but the name was kept in sales literature on the markets that wasn´t protected by Kreidler. I don´t know exactly which countries were involved though, so it´s a bit complicated to be exact.

we have a bit trouble with amazon anyway, as we have lots of them as Amazon actually, but according to this: http://www.volvoclub.org.uk/prof_120.shtml
the designation was dropped after two years in production..

http://www.volvop1800club.se/eng/index.htm - very useful, year by year, I use it myself

Volvo Amazon identification guide. Unfortunately only in swedish, but there are some illustrating pictures.