Perhaps you should try some spelling variations:
"coder coder sampling study protocol" » "coder under sampling study protocol" (Expand search), "coder over sampling study protocol" (Expand search), "coder core sampling study protocol" (Expand search), "coder coder sampling studies protocol" (Expand search), "coder coder sample study protocol" (Expand search), "coder decoder sampling study protocol" (Expand search), "code code sampling study protocol" (Expand search), "decoder codec sampling study protocol" (Expand search)
"_ python python python programming" » "_ pythons python python programming" (Expand search), "_ piton python python programming" (Expand search), "_ pitons python python programming" (Expand search)

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("coder coder sampling study protocol") OR ("_ python python python programming"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"coder coder sampling study protocol\") OR (\"_ python python python programming\"))".
• Removing quotes may allow a broader search: (( coder coder sampling study protocol ) OR ( _ python python python programming )).
• Adding a wildcard symbol may retrieve word variants: (("coder coder sampling study protocol") OR ("_ python python python programming"))*.