Angelic Voices

Creatures you control get +1/+1 as long as you control no nonartifact, nonwhite creatures.

Masters Edition IV

Chronicles Foreign Black Border

Chronicles

As long as the only creatures you control are white or artifact creatures, all creatures you control get +1/+1.

Legends

As long as the only creatures you control are white or artifact creatures all your creatures gain +1/+1.

You get the bonus if all of your creatures are white or artifact even if they also have other colors or qualities. So, if your only creature is a white and green creature, or a red artifact creature, you would get the bonus.