Talvez deva tentar algumas variações de ortografia:
recurrent never » recurrent fever (Expandir a Pesquisa), recurrent severe (Expandir a Pesquisa), recurrent fevers (Expandir a Pesquisa)
content serve » content server (Expandir a Pesquisa), content series (Expandir a Pesquisa), content services (Expandir a Pesquisa)
never system » lever system (Expandir a Pesquisa), server system (Expandir a Pesquisa), river system (Expandir a Pesquisa)
a recurrent » _ recurrent (Expandir a Pesquisa)
best serve » best served (Expandir a Pesquisa), best service (Expandir a Pesquisa), best steve (Expandir a Pesquisa)
serve case » nerve case (Expandir a Pesquisa), service case (Expandir a Pesquisa), nerve cases (Expandir a Pesquisa)
serve can » merve can (Expandir a Pesquisa), nerve can (Expandir a Pesquisa), service can (Expandir a Pesquisa)
system di » system de (Expandir a Pesquisa), system d (Expandir a Pesquisa), system dias (Expandir a Pesquisa)
can diet » can direct (Expandir a Pesquisa), than diet (Expandir a Pesquisa)
case dis » case disc (Expandir a Pesquisa), case di (Expandir a Pesquisa), case does (Expandir a Pesquisa)

You can also try:

• Europeana
• Digital Public Library of America
• CORE

Pode obter mais resultados ajustando a pesquisa.

• Se usar operadores Booleanos, por favor insira-os com letras MAIÚSCULAS: (((( i content serve can diet ) OR ( a recurrent never system di ))) OR ( j best serve case dis ))~.
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (((( i content serve can diet ) or ( a recurrent never system di ))) or ( j best serve case dis ))*.