From researching, I have found the following key texts which relate to sound within animation:
This blog entry speaks about how music connects us to a scene, and because of this, it is usually the music that we remember first rather than the visuals. A few examples included in this blog entry includes Jaws, Snow White and the Seven Dwarfs, and also the themes for Freddy Krueger and Darth Vader. These are examples where when mentioned, you instantly think of the music associated to the film, such as ‘Heigh-Ho’ and the ‘Imperial March’ for the Seven Dwarfs and Darth Vader respectively.

This reiterates a quote from Michel Dougherty in ‘The Animation Book’ by Kit Laybourne, which is:

A truth whispered among animators is that 70% of a show’s impact comes from the sound track.

EDIT: 22/10/2014

Today I met up with the rest of our group to do some more research in the library. Together, we found a range of books that were very helpful to us, albeit some texts recapitulated that music has a large significance in animation and shouldn’t be left to the very end, instead planning it in pre-production.

These texts were:
“Sound Design. The Expressive Power of Music, Voice, and Sound Effects in Cinema” David Sonnenchein
“Pre-Animate! The Guidebook for Independent Animators” Raren McCann
“Sound with Vision. Sound techniques for television and film” E.G.M. Alkin
“Sound Theory, Sound Practise” Rick Altman
“Storytelling Through Animation” Mike Wellins
“Reading the Rabbit. Explorations in Warner Bros. Animation” Kevin S. Sandler
“Animated Films” James Clarke
“Understanding Animation” Paul Wells
“Creating 3D Animation” “Get Started in Short Filmmaking. Principles practice and techniques: an inspiration guide for aspiring filmmaker”
“Animation Techniques” Richard Taylor