2. The year of first publication of the work. In the case of compilations or derivative works incorporating previously published material, the year date of first publication of the compilation or derivative work is sufficient. The year date may be omitted where a pictorial, graphic, or sculptural work, with accompanying textual matter, if any, is reproduced in or on greeting cards, postcards, stationery, jewelry, dolls, toys, or any useful article; and
The “C in a circle” notice is used only on “visually perceptible copies.” Certain kinds of works—for example, musical, dramatic, and literary works—may be fixed not in “copies” but by means of sound in an audio recording. Since audio recordings such as audio tapes and phonograph disks are “phonorecords” and not “copies,” the “C in a circle” notice is not used to indicate protection of the underlying musical, dramatic, or literary work that is recorded.