Perhaps you should try some spelling variations:
"coder model using cone sampling" » "coder model using core sampling" (Expand search), "coder model using one sampling" (Expand search), "coder model using line sampling" (Expand search), "cover model using cone sampling" (Expand search), "decoder model using cone sampling" (Expand search), "copper model using cone sampling" (Expand search)
"in python python python programming" » "in pythons python python programming" (Expand search), "in piton python python programming" (Expand search), "in pitons python python programming" (Expand search), "_ python python python programming" (Expand search)

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: "((\"coder model using cone sampling\") OR (\"in python python python programming\"))~".
• Removing quotes may allow a broader search: (( coder model using cone sampling ) OR ( in python python python programming ))~.
• Adding a wildcard symbol may retrieve word variants: (("coder model using cone sampling") OR ("in python python python programming"))*.