Perhaps you should try some spelling variations:
original references » origin references, origins references, marginal references
signals references » goals references, minerals references, pitfalls references
einer original » eines originals, either original, ein original
elgar signals » clear signals, pulsar signals, radar signals

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: (( einer original references ) OR ( elgar signals references )).
• Adding a wildcard symbol may retrieve word variants: (( einer original references ) or ( elgar signals references ))*.