References are the basis of all material on Wikipedia. It's the only way to deal with bias at a global level. Your friend might be a decent person but there are lots of Commissioners of Public Works that aren't and have agendas that take a non trivial amount of effort and time to discover.
Printed references are references, and they shouldn't be rejected just because they aren't on the internet. But even when the author went to the trouble of putting those references on the internet, they were still deleted.
There's just no justification for that. Even if a policy required all references to be available via the internet, the author fulfilled that requirement.
sigh...there is justification. Which doesn't mean your friend and his content were treated shabbily.
If this was allowed, and Donald Trump is putting up his documents on the internet and referencing them on his wikipedia page would you allow it? It can do a lot of damage and people and organizations do this all the time and every day.
If something has has been officially published, and is available to the public, it's a reference. That's entirely distinct from someone citing their own stuff.
