Prior to 1978, the following was required for copyright protection (see United States Copyright Office page 2):

"Visually Perceptible Copies The notice for visually perceptible copies should contain all three elements described below. They should appear together or in close proximity on the copies.

1 The symbol © (letter C in a circle); the word “Copyright”; or the abbreviation “Copr.”

2 The year of first publication. If the work is a derivative work or a compilation incorporating previously published material, the year date of first publication of the derivative work or compilation is sufficient. Examples of derivative works are translations or dramatizations; an example of a compilation is an anthology. The year may be omitted when 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 useful articles.

3 The name of the copyright owner, an abbreviation by which the name can be recognized, or a generally known alternative designation of owner.1 Example © 2007 Jane Doe.")

Carefully studying the front and back scans of this vintage image, which are included in the file history and the source link, show no evidence of #1. It was therefore never under copyright.

Toto je volné dílo, neboť bylo vydáno ve Spojených státech mezi roky 1929 a 1977 bez copyrightové výhrady. Pokud není jeho autor již mnoho let mrtev, je stále autorskoprávně chráněno v zemích, které na americká díla neuplatňují pravidlo kratší doby ochrany, jako jsou například Kanada (50 p.m.a.), Čína (50 p.m.a., netýká se Hongkongu či Macaa), Německo (70 p.m.a.), Mexiko (100 p.m.a.), Švýcarsko (70 p.m.a.) a další země s individuálními smlouvami. Více informací najdete v tomto přehledu. العربية ∙ беларуская (тарашкевіца) ∙ čeština ∙ Deutsch ∙ Ελληνικά ∙ English ∙ español ∙ français ∙ Bahasa Indonesia ∙ italiano ∙ 日本語 ∙ 한국어 ∙ македонски ∙ Nederlands ∙ português ∙ русский ∙ sicilianu ∙ slovenščina ∙ ไทย ∙ Tiếng Việt ∙ 中文（简体） ∙ 中文（繁體） ∙ +/−