The Lutheran confessions cite the deuterocanonicals to prove matters of doctrine.
That never made sense for me when I first discovered that fact. Luther rejected them, but Melancthon seemed to accept them.
The Apology of the Augsburg Confession qoutes from two books of the Deuterocanonicals, but only in response to the Pontificia Refutatio. What doctrine do you think Lutherans require the Deuterocanonicals to prove?