@Test
public void fromToUnknown() {

    PageRange pr = PageParser.parse("10-??");
    assertEquals("10-??", pr.getLiteral());
    assertEquals("10", pr.getPageFirst());
    assertNull(pr.getNumberOfPages());
    assertTrue(pr.isMultiplePages());
    pr = PageParser.parse("10 - ??");
    assertEquals("10 - ??", pr.getLiteral());
    assertEquals("10", pr.getPageFirst());
    assertNull(pr.getNumberOfPages());
    assertTrue(pr.isMultiplePages());
}