THE SOLUTION

To solve the riddle, fill in all of the authors who wrote the books listed. Once the letters of the author names are all filled in, write out all of the letters in order - top to bottom, right to left. You get this:

th oe glsm cssrsvhi rotthirteen oneeofiorlgcajch bwrvibfvynlwhsooauid rlaenbieeeariryrxbbo oidnbenryyimwcrlrsy nnsesssoeeoeoel tgoctvllywne enkilln e

The only immediately evident word is "thirteen." But "thirteen" has something else in its line with it: "rot". A Google search reveals that "Rot 13" is a letter substitution code in which each letter of the code replaces the letter 13 letters after it in the alphabet, suggesting that the letter sequence is actually encoded.
Rot 13 deciphering tools are readily available online. At www.rot13.com, for instance, you can enter in the coded letter sequence and decipher it. When you decode the letter sequence above, it looks like this:

gubrtyfzpffefiuvebgguvegrrabarrbsvbeytpnwpuojeivosilayjufbbnhvqeynraovrrrnevelekoobbvqaoraellvzjpeyeflaafrfffbrrbrbrygtbpgiyyljarraxvyyar

Do you see the "nevelekoob" in there? It's backwards. What else is backwards?

gubrtyfzpffefiuvebgguvegrrabarrbsvbeytpnwpuojeivosilayjufbbnhvqeynraovrrrnevelekoobbvqaoraellvzjpeyeflaafrfffbrrbrbrygtbpgiyyljarraxvyyar

Putting the letters the right way gets you this:

rayyvxarrajlyyigpbtgyrbrbrrbfffrfaalfeyepjzvllearoaqvbbookelevenrrrvoarnyeqvhnbbfujyalisoviejoupwnptyebvsbrrabarrgevuggbevuifeffpzfytrbug

Going back to the original list of books, book eleven is Frankenstein.
The key was in the Aliso Viejo library branch in a copy of Frankenstein.