Perpetual calendars: how to determine which day of the week a given date was (or will be).
A chart of the days of the week in 160 languages throughout world history. This chart, first published in 1896, is now available in larger format—we have digitally enhanced it, and have provided a way for you to print out the small-font version or to order the larger version, on seven ledger-size sheets.
Copyright is also related to the passage of time. When does something lose its copyright and become available to use under public domain? Peter Hirtle, Archivist at Cornell University, has updated his very useful chart. Anything that was published before 1923 is in the public domain. In addition, anything published between 1923 and 1977 without a copyright notice is in the public domain. Lolly Gasaway's chart is a helpful shorter chart.
A chart of the days of the week in 160 languages throughout world history. This chart, first published in 1896, is now available in larger format—we have digitally enhanced it, and have provided a way for you to print out the small-font version or to order the larger version, on seven ledger-size sheets.
Copyright is also related to the passage of time. When does something lose its copyright and become available to use under public domain? Peter Hirtle, Archivist at Cornell University, has updated his very useful chart. Anything that was published before 1923 is in the public domain. In addition, anything published between 1923 and 1977 without a copyright notice is in the public domain. Lolly Gasaway's chart is a helpful shorter chart.