CPC Subgroup
E21C 37/20 by ultrasonic waves
Full Title
Other methods or devices for dislodging with or without loading (breaking-down by means inserted in slits E21C27/14) > by ultrasonic waves
E21C 37/20 Other methods or devices for dislodging with or without loading (breaking-down by means inserted in slits E21C27/14) > by ultrasonic waves