Best to link to the one on bitcoin.com: https://www.bitcoin.com/bitcoin.pdf
> curl 'https://www.bitcoin.com/bitcoin.pdf' | md5
> curl https://bitcoin.org/bitcoin.pdf | md5
Of the two organizations, .org seems far more trustworthy.
https://www.bitcoin.com/about-us: "Please keep in mind that this is a commercial website"
https://bitcoin.org/en/about-us: "Bitcoin.org was originally registered and owned by Bitcoin's first two developers, Satoshi Nakamoto and Martti Malmi. When Nakamoto left the project, he gave ownership of the domain to additional people, separate from the Bitcoin developers, to spread responsibility and prevent any one person or group from easily gaining control over the Bitcoin project."