The MMC-20CL was a very successful B&O cartridge and received a lot of good audio reviews. Obviously it was designed to integrate perfectly with the B&O Beogram turntables at the time but it was sold with cartridge mounting hardware for other, none B&O tonearms. The "-B" and "-C" suffix on the packaging indicates this. "-B" included an adapter for a 1/2 inch phono cartridge shell. "-C" included an adapter for universal tonearms. All of the MMC-20CL identified cartridges are the same.
For reviews of the MMC-20CL other than B&O brochures you will find reviews in these audio magazines (in the USA). I'm sure there were reviews in audio magazines of other countries.
High-Fidelity Magazine - April 1979, Page 32
Audio Magazine - March 1980, Page 78.
Stereo Review Magazine - June 1979, Page 44 (MMC-20CL)
Stereo Review Magazine - June 1981, Page 38 (MMC-20CL along with the Beogram 8000)
The Stereo Review and High Fidelity magazine articles from 1979 are the best.
-sonavor