George Von Rauch,

A history of Soviet Russia, Fifth Revised Edition, 1967

The same night two prominent Kadet leaders, Professor F. Kokoshkin, and Dr. A. Shingarev, were murdered in a hospital by a group of Bolshevik sailors. When Lenin heard of the ensuing protest meetings held by the Social Revolutionaries and the Mensheviks, he said cynically: 'Let them protest, let them bubble over with rage, let them rave some, sigh some, drink a lot of tea and talk until dawn; then they will surely soon fall asleep.'