Unaddressed printed matter.

Addressed printed matter.

Letter.

Press advertising with order form.

Catalogue.

Telephone with human intervention.

Telephone without human intervention (automatic calling machine, audiotext).

Radio.

Videophone (telephone with screen).

Videotext (microcomputer and television screen) with keyboard or touch screen.

Electronic mail.

Facsimile machine (fax).

Television (teleshopping).