The proceedings of the Thirteenth Marcel Grossmann Meeting of Stockholm, Sweden (July 1 – 7, 2012), published by World Scientific Singapore in three volumes, are ready and will be on sale from March 2015. A preview here: http://www.worldscientific.com/worldscibooks/10.1142/9194
These proceedings included contributions from 33 morning plenary talks during 6 days, and 75 parallel sessions over 4 afternoons.
A global program of the meeting is available here: