def get_internal_urls(self):
internal_urls = self.get_subfields("<STR_LIT>", "<STR_LIT:u>", i1="<STR_LIT:4>", i2="<STR_LIT:0>")<EOL>internal_urls.extend(self.get_subfields("<STR_LIT>", "<STR_LIT:a>"))<EOL>internal_urls.extend(self.get_subfields("<STR_LIT>", "<STR_LIT:u>"))<EOL>return map(lambda x: x.replace("<STR_LIT>", "<STR_LIT:&>"), internal_urls)<EOL>
URL's, which may point to edeposit, aleph, kramerius and so on.

Fields ``856u40``, ``998a`` and ``URLu``.

Returns:
    list: List of internal URLs.