i almost never reference... but i always give credit to the artist when i do, it's both polite and respectable to do, it's also logical for someone like me who takes thievery very seriously, considering i've had a few pieces stolen from me in real life...

it hurts, that's something i put time and effort into and by taking it, it's basically spitting in my face!

it's very important to give credit where credit is due!