Inventor: Scheffers, Robertus
Inventor: Scheffers, Robertus
Inventor: Bak, Elly, Steur, Nicolaas D. M.
Inventor: Bak, Elly, Steur, Nicolaas D. M.
Inventor: Stevenson, John
Inventor: Ritchie, John Stanley, Ritchie, Kathleen Anne
Inventor: Ernest D. Williams