34 Thinicons Free PSD
34 Thinicons Free PSD is a free Icon design resource made by Dribbble user Alexandru Stoica. As far as I can tell, its license is Unknown.
Helpful hint: Dribbble users are nice. If the license is unknown, it is usually because they forgot to mention it explicitly; not because they were being stingy. Ask nicely and they will probably allow you to use it.