Using multiple arguments for string formatting in Python (e.g., ‘%s … %s’)

Mark Cidade’s answer is right – you need to supply a tuple.

However from Python 2.6 onwards you can use format instead of %:

'{0} in {1}'.format(unicode(self.author,'utf-8'),  unicode(self.publication,'utf-8'))

Usage of % for formatting strings is no longer encouraged.

This method of string formatting is the new standard in Python 3.0, and should be preferred to the % formatting described in String Formatting Operations in new code.