Also posted at:
- wiki.bbchallenge.org/w/index.php?title=Antihydra&oldid=958 But obviously it got deleted, not even a tiny shitpage maintained by 5 people is immune to it.
- cstheory.stackexchange.com/questions/20978/what-is-the-smallest-turing-machine-where-it-is-unknown-if-it-halts-or-not/53326#53326
- cs.stackexchange.com/questions/59344/what-are-very-short-programs-with-unknown-halting-status/162108#162108
Ciro Santilli got his hands on this one. But he was unable to obtain the others. Solving them here would also pose a serious DMCA risk, so perhaps it's just not worth it.
Toshiba D-088 dental X-ray tube
. Source. 
How Does X ray Tube Works by BiomedEngg
. Source. Describes in particular the rotating cathode method. Interesting observation that this is especially important since the cathode cannot cool quickly due to the vacuum. There are unlisted articles, also show them or only show them.