Inventor: Scheffers, Robertus
Inventor: Scheffers, Robertus
Inventor: Bak, Elly, Steur, Nicolaas D. M.
Inventor: Bak, Elly, Steur, Nicolaas D. M.
Inventor: Jacob, Helmut B.
Inventor: Wandell, Willet N.
Inventor: Wandell, Willet N.
Inventor: Ernest D. Williams