Perhaps you should try some spelling variations:
"skip sampling" » "skin sampling", "chip sampling", "stop sampling", "skinp sampling"
"skip jumping" » "stop jumping", "i jumping", "ii jumping", "skinp jumping"
"ski jumping" » "skin jumping"

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: (("ski jumping") OR ((("skip jumping") OR ("skip sampling")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"ski jumping\") or (((\"skip jumping\") OR (\"skip sampling\"))))".
• Removing quotes may allow a broader search: (( ski jumping ) or ((( skip jumping ) OR ( skip sampling )))).
• Adding a wildcard symbol may retrieve word variants: (("ski jumping") or ((("skip jumping") OR ("skip sampling"))))*.