2nd edition
https://archive.org/details/introduction-to-quantum-mechanics-griffiths/page/394/mode/2up

1st edition start pg 367
https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxtZWNhbmljYWN1YW50aWNhMjAxNDJ8Z3g6MzQxNzgyYzgxOTVjMDY1Nw