(JTA) — A banner towed by a plane over the tailgate party of the University of Oklahoma’s opening football game called for University President David Boren to “#returnthestolen art.” The banner flown for about two hours on Saturday, Sept. 5, refers to a piece of artwork donated to the university that is believed to have been stolen by the Nazis from a Jewish family.

Camille Pissaro’s “Shepherdess Bringing in Sheep” was donated to the university by Clara Weitzenhoffer upon her death in 2000, and has been hanging in the university’s Fred Jones Jr. Museum of Art since then. The 1886 painting, one of 33 donated to the museum from Clara and Aaron Weitzenhoffer’s extensive collection of French Impressionist art, belonged originally to Jewish French department store owner Raoul Meyer. Meyer’s entire art collection was seized by the Nazis when they invaded France during World War II.

The flyover banner was sponsored by the Virginia-based group Americans for Limited Government, which called on Boren to “set a good example for his students.” Americans for Limited Government President Rick Manning said Saturday in a statement, “OU [Oklahoma University] President David Boren should act immediately to return the artwork in his University’s possession that was stolen by the Nazis from a Jewish family. While OU obtained the art through a legal donation, it is unconscionable that they are spending tens of thousands of dollars in attorney’s fees to keep it from its rightful owner,” he said.

“Shepherdess Bringing in Sheep” changed hands several times before a Swiss court ruled in 1953 that Meyer had missed his five-year window to recover the painting. Meyer’s daughter, Leone, filed a lawsuit against the University of Oklahoma in January 2014 in order to recover the painting.

Boren, in a statement published in the student newspaper, the Oklahoma Daily, called the flyover “an unfair attempt to simplify the issue. Two very fine families are involved in this issue. The University is seeking a solution that will be fair to the family that first lost the art and to the family which purchased it in good faith and gave it to the OU Foundation so that the public could enjoy it free of charge.”