Persian and Greek Interaction post Greco Persian

Earlier i posted a thread about Alexander but i am now switching to a second topic my professor provided me which how the persian empire influenced early Greek politics after the Greco Persian wars. One example he gave me is how Sparta went to the persians to ask for help in the pelopenisian wars and provided them with ships which tipped one of the battles in their favor. I can only use primary sources and have no idea where to start so any help is of great appreciation. Thanks so much for reading!