Extracting book information from a web page, with possible missing attributes
The obvious thing to do when you have repeated functionality is to extract it into a function. In this case, it looks like the parameters for the function are the content itself, the element type to find, the classname, and a list of text to replace.

You can also tidy things up by only doing the find once.

def find_text(content, element, classname, *replacements):
    item = content.find(element, {'class': classname})
    if item:
        text = item.get_text()
        for replacement in replacements:
            text = text.replace(replacement, "")
        return text
    else:
        return 'None'


Now your main loop looks like:

for content in book_info:
    title = find_text('span', 'fn')
    author = find_text('div', 'fieldRow jr_autorestr', "Autore")
    classification = find_text('div', 'fieldRow jr_narrstrcontinente', "Classificazione")
    ... etc ....