Kelvin Smith Library
This is a rare case in which I recommend a Wikipedia page!
Specifically, the Wikipedia page Bibliography of Fly Fishing books is a good one to find books on specific topics and from specific time periods.
For those books that were published before 1924 and are out of copyright, links are provided to the online full text. For newer books, search for the titles in OhioLINK to borrow them from other libraries if we do not own them.
While the list mentioned above does a great job of providing access to books on fly fishing, sometimes one needs to search for oneself!
There are several online collections that can be useful in this case.
OhioLINK E-Book Center- a collection of tens of thousands of full text books, primarily reference and academic titles.
Google Book Search- full text books limited to only those published before 1923 (out of copyright) as well as "preview" content of newer books.
Internet Archive- a warehouse of many different kinds of media, but their e-book collection has many titles of use, again, primarily for those materials that are out of copyright.