Talvez deva tentar algumas variações de ortografia:
does develop » boys develop (Expandir a Pesquisa), loss develop (Expandir a Pesquisa), res develop (Expandir a Pesquisa)
develop them » develop type (Expandir a Pesquisa), develop age (Expandir a Pesquisa)
naive levels » native levels (Expandir a Pesquisa), five levels (Expandir a Pesquisa), have levels (Expandir a Pesquisa)
levels other » levels another (Expandir a Pesquisa), levels rather (Expandir a Pesquisa), levels over (Expandir a Pesquisa)
doses liver » does liver (Expandir a Pesquisa), dose liver (Expandir a Pesquisa), dose live (Expandir a Pesquisa)
drug doses » drug dose (Expandir a Pesquisa)
liver ther » liver other (Expandir a Pesquisa), liver rather (Expandir a Pesquisa), live rather (Expandir a Pesquisa)
drug does » drugs does (Expandir a Pesquisa), drug dose (Expandir a Pesquisa), drug de (Expandir a Pesquisa)

You can also try:

• Europeana
• Digital Public Library of America
• CORE

Pode obter mais resultados ajustando a pesquisa.

• "As palabras AND, OR e NOT podem gerar pesquisas incorrectas; tente utilizar aspas": "(( drug does develop them ) OR ((( drug doses liver ther ) OR ( drug naive levels other ))))~".
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (( drug does develop them ) OR ((( drug doses liver ther ) OR ( drug naive levels other ))))*.