* {{cite web |first=Grant |last=Sanderson |title=But what is a partial differential equation? |work=3Blue1Brown |date=April 21, 2019 |url=https://www.youtube.com/watch?v=ly4S0oi3Yz8&list=PLZHQObOWTQDNPOjrT6KVlfJuKtYTftqH6 |via=YouTube }} | * {{cite web |first=Grant |last=Sanderson |title=But what is a partial differential equation? |work=3Blue1Brown |date=April 21, 2019 |url=https://www.youtube.com/watch?v=ly4S0oi3Yz8&list=PLZHQObOWTQDNPOjrT6KVlfJuKtYTftqH6 |via=YouTube }} |