Wool Blend

How can I lighten vintage wool sweaters that have yellowed with age to get the yellow out?

Purchased 2 beautiful icelandic vintage sweaters each has a cream background but the cream looks a bit yellowed with age. Does anyone know of a way to minimize this look or remove/ restore the true color. 1 sweater is wool the other a wool blend. I heard of something called mrs. stewarts liquid bluing ( or something like that) has anyone used this? any other suggestions?

Bluing gives a blue hue to white which makes the whiter look whiter. I would test it on a small hidden bit of the sweater first. Ammonia and water might help remove the yellow too, test that first also.

Siena Studio Wool Blend Coat with Animal-Print Lining