A corrected and enlarged version has been published as: H.A.G. Houghton, Augustine's Text of John. Patristic Citations and Latin Gospel Manuscripts. (Oxford Early Christian Studies) Oxford: OUP, 2008. ISBN 978-0-19-954592-6. http://ukcatalogue.oup.com/product/9780199545926.do? Also published as an e-book at: 
http://www.oxfordscholarship.com/oso/public/content/religion/9780199545926/toc.html