Talvez deva tentar algumas variações de ortografia:
sampling density » sampling intensity (Expandir a busca), sampling design (Expandir a busca), stocking density (Expandir a busca)
system decrease » system decreases (Expandir a busca), system increase (Expandir a busca), symptom decrease (Expandir a busca)
density python » density method (Expandir a busca)
python system » action system (Expandir a busca)
python python » pythons python (Expandir a busca), piton python (Expandir a busca), pitons python (Expandir a busca)

Você pode obter mais resultados ajustando o argumento de busca.

• Remover as aspas pode possibilitar buscas mais amplas: (( sampling density python system decrease ) OR ( _ python python python programming ))~.