What I do largely depends on the media in question.
I have all of my main books in (full-text searchable) e-book format:
- The Lord of the Rings trilogy, The Hobbit, etc.
- All seven Harry Potter books, plus the Cursed Child and Fantastic Beasts published scripts and the three Pottermore e-books
- Most of the canon Star Wars books and novelizations, and several of the Legends novels
Typically I've acquired them in ePub or Mobi format, in which case I use online tools to convert them to PDFs (which have better cross-platform tools).
I also have ready access to a pretty good public library, so I'll often pop over there on my lunch break to check some of the books I don't have, or I'll simply pull a physical book off my shelf (especially when I'm citing Lord of the Rings: A Reader's Companion or The Annotated Hobbit) when I'm at home; doing this usually requires me to have a pretty good idea of where in the book I'm looking, though.
If all else fails, and especially for obscure books, I occasionally make use of Google Books' free preview feature; I prefer not to do this, because of how I prefer to cite sources, but I've done it on occasion.
If you're referencing older books, you may have a chance of finding them on Project Gutenberg, or one of its international affiliates; these sites mostly have books that have passed into the public domain, which largely limits them to works published in the 1920s and earlier.
Unfortunately, no recourse here but manual transcription; fortunately I get all my comics digitally, so it's not that much of an imposition.
Many films have screenplays online; IMSDB is a good resource for this, though they don't always have the final versions (something which has bitten me before). Many film transcripts can also be found at Springfield Scripts, though with the caveats I'll cover in the next section.
Occasionally I also simply pull the film up on my computer, rely on my memory to guide me to the right moment, and transcribe by hand.
For Star Trek, chakoteya.net has full transcripts (including some minimal stage direction) for all episodes and the films.
ST Minutiae also has downloadable text files of the original scripts (compiled from assorted published sources) for the TOS- and TNG era films, The Next Generation, Deep Space Nine, and a handful of Voyager episodes; I don't use these as often, because the chakoteya transcripts usually suffice, but sometimes the stage directions are relevant
For Doctor Who, again I use chakoteya.net. All the old episodes (including the classic series), TV specials, spinn-offs, and The Film have archived transcripts; new episodes are usually added within a day or two
On the rare occasion I answer a Stargate question, the SG-1 Solutions wiki has a comprehensive transcript library of all three shows
For Supernatural, Super-wiki has full transcriptions of all episodes, generally updated often enough for my purposes
For other shows, I sometimes use Springfield Scripts; however, this site suffers from some problems:
- It only transcribes dialogue, not any stage direction or activities; most crucially, it also doesn't specify who's saying each line
- Every so often they have database issues, leaving them largely useless for a few days until they can recover
So I typically have to supplement them with either memory or manual transcription from re-watching the episode.
For this, I typically rely on Let's Play videos on Youtube. This can be rather tedious, but fortunately I don't have to do this very often
This is largely Google-fu; I don't make a habit of reading interviews, but there's enough pop culture reporting that interviews are fairly easy to find on Google.
For Harry Potter specifically, Accio Quote is a good resource for JK Rowling interviews, but hasn't been updated since 2012.
I follow Pablo Hidalgo on Twitter1, which is:
- Very informative for Star Wars tidbits
- Hilarious; I have a deep appreciation for his dry, long-suffering humour
So I typically have a fuzzy memory of his recent tweets, which is helpful for answering recent questions; Twitter's built-in search mechanism makes it relatively easy to find the exact tweet.
For others, I typically fall back on Google. I know that I could follow JK Rowling, but the ratio of "useful canon" to "political opinions" is low enough that I don't care to bother.
1 I also follow Leland Chee and Matt Martin, Hidalgo's compatriots in the Lucasfilm Story group; but Hidalgo spends much more of his Twitter-time responding to lore questions, so I generally find him more useful.