Gohar Vardanyan (sponsored by Strings by Mail) performs and teaches a lesson for Etude No. 23, Op. 38 by Napoléon Coste (1805–1883). This comes via her YouTube channel where she has been posting a number of etude lessons (check it out and subscribe). Vardanyan’s technique, filled with controlled articulation, works well for this etude and you can pick up many ideas about detached articulations and muting techniques.