1

is there a possibility to use the skeleton from the side and not from the front

2

What do you mean with "skeleton" ?

3

in observation-reference you can select a human-skeleton
thats the skeleton i mean

4

Ha ! I had forgotten about that one smile
Well I don't know where to find a side view but if you can find one in SVG or other image format, you may import it.
I did find a bunch of anatomy files here and there (Wikimedia Commons), but there is no side view skeleton.