A museum rarely publicizes its doubts about rights to works in its collection—but that’s what Amsterdam’s Stedelijk Museum is doing in an exhibition that opens Friday.

“The Stedelijk Museum in the Second World War” recounts the daring ways in which the museum’s employees fought Nazi censors after Germany conquered the Netherlands in May 1940. But the show also features 16 works in the permanent collection by artists including Paul Klee, Wassily Kandinsky and Henri Matisse that the museum says it might not rightfully own.