Our servers are currently under attack from someone who runs a denial of service attack: https://en.wikipedia.org/wiki/Denial-of-service_attack
For security reasons, our servers shut down in such a case. That’s the reason why some of our databases currently do not return any or only partial results. We’re working on it and we’ll endeavor to fix this as soon as possible.
Please accept our apologies for the inconvenience caused.
Update: the problems have been solved.