https://www.fanfiction.net is the home for hundreds of thousands of fan written stories for every possible TV, Movie, video games etc (126,000 Supernatural stories for example), obviously most of it is total shit but you'd be surprised at how much bondage there is dotted about.
The other resource is the gutenberg.org project which has over 60,000 free ebooks that are out of print, mostly the 19th and early 20th century with lots of swashbuckling adventure, westerns and detective novels that seem to have loads of tying up (and casual racism/sexism).
The trick is to use google to perform a site search. i.e. the following produces 12K results.
>type in google> "bound and gagged" site:fanfiction.net
if you add another search term in that is narrowed down to 200 odd hits for example
> "bound and gagged" hogtie site:fanfiction.net
There's as many misses as hits in this but you can add in tags like rope ankles wrists etc to narrow or widen your search.
Using this method you can hone in on your own person kink I guess. As mentioned the other site is gutenberg.org. An example of a search in google that brings back 137 is "hog-tie" "boots" site:gutenberg.org - my personal favourite
Not all of the books it finds will have tie-ups in them but many will.
The hits will take you the html doc that you can then do a search for the section of the text. Other tips are that putting stuff in " " will give you an exact match whereas leaving the quotes off google will do a fuzzy search i.e. will give hits for Shoes as well as boots in the text so you may have to experiment with how best to find your long lost literary titilation.
