Google & Thesaurus.com
You wouldn't believe the unusual things you must look up when writing a book.
I have researched the National Art Gallery of Canada, Ottawa, Ontario bus routes, restaurants in Montreal and what kind of wine they serve. I contacted my rowing partner from 25 years ago on entry requirements for the Head of the Charles Regatta in Boston, Massachusetts and studied the race course and the many boathouses along the way.
Two tabs were always open on my computer as I wrote. I set one to Thesaurus.com, and the other was ready to Google whatever I needed to know more about. Like, that thing you use to bolt a door; it's called a thumbturn if you were wondering.