I'd be willing to bet I know exactly the pencil sketch you're referring to. 

 

Before everyone gets scared of cutting stuff or creating patterns I just want to point out that there are tons of public domain resources available which are all perfectly legal to design patterns from (and sell if you so desire).  If you're using an artist's drawings or another photographer's photos, you should have permission from that artist or photographer to create the pattern (provided it was published after 1922).  Anything published in the US prior to 1923 is in the public domain.  For most European countries, anything published (in that country) prior to 1957 is in the public domain.

 

Kevin