Perhaps you should try some spelling variations:
earth references » research references, further references, growth references
elgar reference » stellar reference, lunar reference, error reference
ear references » shear references, air references, nmr references
ar reference » r reference, air references, war references

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 reference) OR (ar reference)) collection ) OR ( ((ear references) OR (earth references)) collection )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((elgar reference) OR (ar reference)) collection ) or ( ((ear references) or (earth references)) collection ))".
• Adding a wildcard symbol may retrieve word variants: (( ((elgar reference) OR (ar reference)) collection ) or ( ((ear references) or (earth references)) collection ))*.