question about references

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i had a doubt so i thought i might as well ask here. when you use references for your drawings, do you think it comes more in handy or more comfortable to have them physically in books or papers?

and also, i was thinking of cropping some different body parts of different works to use as references, kind of like pic related, but i sort of feel weird of working with stuff that's not intended to be used as references you know? like a sheet of poses and boxes is fair games but an actual drawing is something else. i don't know these questions just occurred me because soon i may have access to some free black and white printing so i thought that having some references or tutorial sheets around may be useful