Talvez deva tentar algumas variações de ortografia:
control variables » contextual variables (Expandir a busca)
variables problem » variables problems (Expandir a busca), variable problem (Expandir a busca), variance problem (Expandir a busca)
cotton control » cotton cotton (Expandir a busca)
python python » pythons python (Expandir a busca), piton python (Expandir a busca), pitons python (Expandir a busca)
coder cotton » over cotton (Expandir a busca), under cotton (Expandir a busca), model cotton (Expandir a busca)
in python » _ python (Expandir a busca)

Você pode obter mais resultados ajustando o argumento de busca.

• Remover as aspas pode possibilitar buscas mais amplas: (( coder cotton control variables problem ) OR ( in python python python programming ))~.