Perhaps you should try some spelling variations:
"international photographic observations" » "international photographer observations", "international cartographic observations", "international demographic observations", "international photographies conservation", "international photographs conservation", "international photoelectric observations"
"international photometric observations" » "international econometric observations", "international phonetic observations", "international radiometric observations"

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: "((\"international photographic observations\") OR (\"international photometric observations\"))".
• Removing quotes may allow a broader search: (( international photographic observations ) OR ( international photometric observations )).
• Adding a wildcard symbol may retrieve word variants: (("international photographic observations") OR ("international photometric observations"))*.