text design

Cyrillic (Russian) ideal number of characters per line

Hi Typophiles,

I'm a publisher and designer and need to establish good type design parameters for Russian books. I don't speak Russian and therefore can't come up with settings that Russian readers would consider ideal for sustained reading. For English text and the usual text faces, the ideal number of characters (including spaces and punctuation) is about 67 per line. Has anyone heard of an ideal number for Russian? Grateful for any lead. :)