Perhaps you should try some spelling variations:
"elgar origin references" » "elgar brain references", "algal origin references", "solar origin references", "ear origins references"
"elgar marginal references" » "near marginal references"
elgar signals » clear signals, pulsar signals, radar signals
sonar signals » sonar signal, biosonar signals, sensor signals

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: (((("((elgar signals) or (sonar signals)) references") OR ("elgar origin references"))) OR ("elgar marginal references")).
• Removing quotes may allow a broader search: (((( ((elgar signals) or (sonar signals)) references ) or ( elgar origin references ))) or ( elgar marginal references )).
• Adding a wildcard symbol may retrieve word variants: (((("((elgar signals) or (sonar signals)) references") or ("elgar origin references"))) or ("elgar marginal references"))*.