Perhaps you should try some spelling variations:
chemical institute » mathematical institute, chemical constituents, chemical constitution
central institute » federal institute, memorial institute, federal institutes
federal statutes » general statutes, several statutes, federal state

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((((central institute) OR (federal statutes))) OR (chemical institute)) of labour.
• Adding a wildcard symbol may retrieve word variants: ((((central institute) or (federal statutes))) or (chemical institute)) of labour*.