I need line drawings

I require line drawings for a book I have written.
It is a web course for 8-10 year old children.
I need
1) A line drawing of a boy sitting at a computer
2) A line drawing of a girl sitting at a computer.
3) A line drawing of a laptop on its own.
4) A line drawing of a boy and girl running passed a finish line with hands raised in celebration.
I need to be able to use these drawing exclusively and the artist will be credited.