Perhaps you should try some spelling variations:
"exchanges mathematical guides" » "exchange mathematical guides", "changes mathematical guides", "mechanics mathematical guides", "exchanges mathematical guide", "exchanges mathematical guided", "exchanges mathematical geodesy"
"machines mathematical guides" » "machinery mathematical guides", "chinese mathematical guides", "teaching mathematical guides", "machines mathematical guide", "machines mathematical guided", "machines mathematical geodesy"

Try widening your search to All Fields.

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: "((\"machines mathematical guides\") OR (\"exchanges mathematical guides\"))".
• Removing quotes may allow a broader search: (( machines mathematical guides ) OR ( exchanges mathematical guides )).
• Adding a wildcard symbol may retrieve word variants: (("machines mathematical guides") OR ("exchanges mathematical guides"))*.