Fitxer:Julius Plücker.jpg

Aquest material està en domini públic als Estats Units i als altres països on el dret d'autor s'estén per 70 anys (o menys) després de la mort de l'autor.

Cal incloure una etiqueta de domini públic als Estats Units per indicar perquè aquesta obra és en domini públic als Estats Units. Note that a few countries have copyright terms longer than 70 years: Mexico has 100 years, Jamaica has 95 years, Colombia has 80 years, and Guatemala and Samoa have 75 years. This image may not be in the public domain in these countries, which moreover do not implement the rule of the shorter term. Honduras has a general copyright term of 75 years, but it does implement the rule of the shorter term. Copyright may extend on works created by French who died for France in World War II (more information), Russians who served in the Eastern Front of World War II (known as the Great Patriotic War in Russia) and posthumously rehabilitated victims of Soviet repressions (more information).