Talvez deva tentar algumas variações de ortografia:
research systems » research synthesis (Expandir a Pesquisa)
mental research » dental research (Expandir a Pesquisa), central research (Expandir a Pesquisa), neonatal research (Expandir a Pesquisa)
entner nerve » enteric nerve (Expandir a Pesquisa), after nerve (Expandir a Pesquisa), other nerve (Expandir a Pesquisa)
bent nerve » absent nerve (Expandir a Pesquisa), mental nerve (Expandir a Pesquisa), dental nerve (Expandir a Pesquisa)
systems di » systems do (Expandir a Pesquisa), systems de (Expandir a Pesquisa), systems d (Expandir a Pesquisa)
nerve cn » nerve can (Expandir a Pesquisa), nerve cat (Expandir a Pesquisa), nerve _ (Expandir a Pesquisa)
j mental » j mengual (Expandir a Pesquisa), j mena (Expandir a Pesquisa), j mehta (Expandir a Pesquisa)
nerve c » nerve _ (Expandir a Pesquisa), nerve a (Expandir a Pesquisa), nerve can (Expandir a Pesquisa)
cn dcs » can dcs (Expandir a Pesquisa)
i bent » i benth (Expandir a Pesquisa), i benet (Expandir a Pesquisa), i bento (Expandir a Pesquisa)
c dis » c dias (Expandir a Pesquisa), c disc (Expandir a Pesquisa), c dos (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": "(((( _ entner nerve cn dcs ) OR ( i bent nerve c dis ))) OR ( j mental research systems di ))~".
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (((( _ entner nerve cn dcs ) OR ( i bent nerve c dis ))) OR ( j mental research systems di ))*.