I thought you were converting from pdf to epub?
Code:
(<A name=\d+>\s*</a>)?\s*(<[biu][^>]*>)?\s*Generated\s+by\s+(ABC)?\s+Amber[^<]*(<a\shref=.*?processtext.*?>)?\s*(.*?processtext.*?</a>)?(</[ibu]>)?\s*(<br>\s*)?
That should take care of more variants of the spam, including yours.
Please remove the book from your previous post - it doesn't matter whether you own it, the problem is posting it to a public bulletin board that doesn't condone piracy.