Search Content of eBooks.

You can do this stuff using itextSharp.dll



 iTextSharp.text.pdf.PdfReader r = new iTextSharp.text.pdf.PdfReader(@"C:\1.pdf");          
ITextExtractionStrategy pes = new SimpleTextExtractionStrategy();
string str = PdfTextExtractor.GetTextFromPage(r, 15);
           
str = Encoding.UTF8.GetString(ASCIIEncoding.Convert(Encoding.Default, Encoding.UTF8, Encoding.Default.GetBytes(str)));


But If you have More solution please provide. because this solution convert pdf to text by Page.

This article can provide you the pointers:

http://www.codeproject.com/Articles/14170/Extract-Text-from-PDF-in-C-100-NET