Perhaps you should try some spelling variations:
transfer functions » transfer function (Expand search), pedotransfer functions (Expand search)
extraction method » extraction methods (Expand search)
case extraction » cane extraction (Expand search), phase extraction (Expand search), based extraction (Expand search)
functions case » functions are (Expand search), functions and (Expand search), functions at (Expand search)
python python » pythons python (Expand search), piton python (Expand search), pitons python (Expand search)
using codigo » using indigo (Expand search), using coding (Expand search), using codium (Expand search)

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

• Removing quotes may allow a broader search: (( transfer functions case extraction method ) OR ( using codigo python python programming ))~.