E. F. Johnson Company Manual. Viking CX Operating Manual. Material: paper. Size: 5 1/2" x 8 1/4". Description: gray and white cover; black and white photograph of the Viking CX; black print: "EFJohnson, Viking CX, Operating Manual, Warning, Do not place the earpiece to your ear with the keypad cover closed. Refer to "Safety Information" on page 2 for more details"; 76 pages.