Perhaps you should try some spelling variations:
"planar guides to teaching" » "planner guided to teaching", "planar grid to teaching", "planar waveguides to teaching"
"laser guided to teaching" » "laser guide to teaching", "user guided to teaching", "based guided to teaching"

Try widening your search to All Fields.

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: (("planar guides to teaching") OR ("laser guided to teaching")).
• Removing quotes may allow a broader search: (( planar guides to teaching ) or ( laser guided to teaching )).
• Adding a wildcard symbol may retrieve word variants: (("planar guides to teaching") or ("laser guided to teaching"))*.