Where do I get the public key to verify the Bitcoin.org PGP signed message? I've downloaded the Bitcoin client from https://bitcoin.org/en/download

I also downloaded the PGP signed file that shows the SHA256 file signatures:
https://bitcoin.org/bin/bitcoin-core-0.12.1/SHA256SUMS.asc

How do I verify this PGP signed file? When I use the command "gpg --verify SHA256SUMS.asc", I get the message

gpg: Signature made Fri Apr 15 02:37:20 2016 EDT using RSA key ID 36C2E964
gpg: Can't check signature: public key not found

Where do I get the public key?
If you check out https://bitcoin.org/en/download, you'll see some links below the download button: 'Bitcoin Core Release Signing Keys'