Forbidden subgraph characterisation of interval graphs A graph is an interval graph iff it is chordal and asteroidal triple free.
An interval graph is proper interval graph iff it is $K_{1,3}$ free.

However i googled intensely to find a minimal set of forbidden subgraphs for proper interval graphs,but in vain.

My question is : What are the minimal set of forbidden subgraphs for proper interval graphs ?
Any link to journal/paper is welcome.
ISGCI's page on proper interval graphs (from our FAQ) lists a few equivalent classes; one of them is the class of $(C_{n+4}$, $S_3$, claw, net)-free  graphs (see the same website for definitions).