Comment by aspidistra

IANAL, but I was also able to find Knol from Google on the UK IPO search:

http://www.ipo.gov.uk/tmcase/Results/4/EU006911796

and the OHIM website, which as I understand it covers Europe-wide trademarks:

https://oami.europa.eu/eSearch/#details/trademarks/006911796

But like I said, I am not a lawyer, do your own research, consult an expert etc etc...