In all of the crossing of genres, we have largely stayed clear of terms that are particular to other media but, now that you have the perfect primer for beginning your exploration into the world of 2D adventure, let's look across at those terms; starting with books: Now the thing about the potboiler is that, while it is just as racy as yer average comic book, being in printed word form and lasting at least a couple of hundred pages, the idea is that all the action and suspense keeps you reading. Adding pictures and reducing the size to thirty-two pages turns this into something different; it isn't anywhere near as big an investment of the reader's time. So too the airport novel.
But the term thriller is a different story and has been employed in the graphic medium a number of times. In fact there was a series called Thriller. Not that I want to fall into the trap of equating comics with the lurid end of book publishing; it's not all pulp fiction, it could even be literature.
Taken over the complete series, a (comic) book may need an appendix, it may possess a frontispiece The index comes into play at the study level. Comics themselves don't usually contain an index to individual panels but Silver Age Marvel, especially, made judicious (often uproarious)use of footnotes. Not even the multi-story British weekly comics would necessarily have a contents page. Part of the fun was reading each story in turn and working through the mag that way. You pretty soon got to know all the regular strips anyway. To an extent these are like a collection of short stories but the ongoing seriality of many of the stories makes them appear more like periodicals than books.
Any reference is likely to be about comics rather than in a sequential art format. But did you really want a dictionary, thesaurus , or concordance in comic book format? An encyclopedia is different since it utilises a combination of words and pictures to supply its meaning. It is also varied and general in a way that, say, an atlas (yeah, I know) or a cookbook is not.Comics also occasionally deal with non-fiction. Popular are memoirs and biographies. But comics can cover Rod and real and everything beyond. What's on your coffee table?