Chances are you haven’t read Margery McIntyre Flood’s young adult oeuvre, which includes “You Can’t Do Anything Right,” “Mom’s Coffee Smells Like Gin” and “You Would if You Loved Me,” otherwise known as “the birth-control one.” Somehow you missed Jean Fung’s “Protracted” (“about hooking up and engineering at a prestigious university, written by the former sex columnist for The California Tech”) and Pamela McLaughlin’s “Strip Tease” (one of her popular Trang Martinez mysteries), Cubby Greenwich’s “One O’Clock Jump” and John Clitherow’s “Mr. Bluebird.”

Though all these titles appeared this year, you won’t find them at the bookshop or at the Kindle store, because they belong to what might be called the invisible library. This library contains books that exist only between the covers of other books — as descriptions, occasionally as brief excerpts, often simply as titles.

The books named above come from three very different sources. Flood figures in Caitlin Macy’s story “Bad Ghost” (from her collection “Spoiled”), a psychologically astute story in which a young woman recalls a fraught spell baby-sitting the author’s daughter. The précis of “Protracted” and a tough-as-leather passage of “Strip Tease” are among the many faux fictions in Steve Hely’s “How I Became a Famous Novelist,” a gleeful skewering of the publishing industry and every cliché of the writing life. And Greenwich and Clitherow (as well as Greenwich’s children’s-book-writing wife, Penny Boom, creator of “The Other Side of the Woods”) are characters in Dean Koontz’s “Relentless,” whose plot spirals out from a best-selling author’s bloody feud with a sinister critic to describe a vast cultural conspiracy. (Appropriately enough, it hit the top spot of the real Times best-seller list.) In 2009, the invisible library is as vibrant as ever, with new acquisitions in every genre.

Novelists have long tucked made-up fictions inside their real ones. Sometimes these interior texts inform the plot or enhance the theme, other times they are just lively bursts of color, sparks thrown off during the authorial process. It’s easy to understand the appeal of creating these miniatures. A few deft lines can conjure perfect examples of untutored rawness (Mattie Ross, the 14-year-old heroine of Charles Portis’s “True Grit,” has a manuscript entitled “You will now listen to the sentence of the law, Odus Wharton, which is that you be hanged by the neck until you are dead, dead, dead! May God, whose laws you have broken and before whose dread tribunal you must appear, have mercy upon your soul. Being a personal recollection of Isaac C. Parker, the famous Border Judge”), sublime dullness (“The Purpose of Clothing Is to Keep Us Warm,” in Jorge Luis Borges and Adolfo Bioy-Casares’s “Chronicles of Bustos Domecq”) or anything in between. Why write the whole book when you can get so much mileage out of the title alone?