Perhaps you should try some spelling variations:
biography sermons » biography germany, biographical sermons
rand corporation » said corporation, road corporation, a corporation
biography series » biography pericles, biography sources, biography studies

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "rand corporation ((biography series) OR (biography sermons))".
• Adding a wildcard symbol may retrieve word variants: rand corporation ((biography series) OR (biography sermons))*.