You can use the Program Performance Report to review which programs led to acquiring new names. You can create smart lists and add "Person Source", using filters if you want specific smart lists for specific sources. You can also subscribe to any basic report, such as program performance report, or smart lists. Search on Welcome to Marketo Docs - Marketo Docs - Product Documentation for information on building smart lists or subscriptions.
I also recommend searching the Community for articles on Attribution Reporting if you want to dive deeper.