Talvez deva tentar algumas variações de ortografia:
optimal cancer » optimal care (Expandir a Pesquisa)
cases included » costs included (Expandir a Pesquisa), cases including (Expandir a Pesquisa), cancer included (Expandir a Pesquisa)
included long » included among (Expandir a Pesquisa), included one (Expandir a Pesquisa), including long (Expandir a Pesquisa)
cancer index » cancer induced (Expandir a Pesquisa), cancer induces (Expandir a Pesquisa)
index monogr » index motor (Expandir a Pesquisa), index monitor (Expandir a Pesquisa), index among (Expandir a Pesquisa)
nat cases » natal cases (Expandir a Pesquisa), what cases (Expandir a Pesquisa), east cases (Expandir a Pesquisa)
j optimal » _ optimal (Expandir a Pesquisa), i optimal (Expandir a Pesquisa), 2 optimal (Expandir a Pesquisa)
e nat » e nata (Expandir a Pesquisa), e nao (Expandir a Pesquisa), e nas (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": "(( e nat cases included long ) OR ( j optimal cancer index monogr ))~".
• Se adicionar um carácter universal pode recuperar variações da palavra pesquisada: (( e nat cases included long ) OR ( j optimal cancer index monogr ))*.