Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cam quoc » cac quoc, cao quoc, nam quoc
quoc ban » quoc bao, quoc lan, quoc quan
ban hanh » ban hang
hanh dai » hanh tai, hanh dao, vanh dai
nano xa » nano va, nano bac, nano cau
hieu va » hieu qua
cua te » cua tu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) truc nano xa hoi. ((lieu va) or (hieu va)) cam quoc ban hanh dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) truc nano xa hoi. ((lieu va) OR (hieu va)) cam quoc ban hanh dai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) truc nano xa hoi. ((lieu va) or (hieu va)) cam quoc ban hanh dai cua te".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) truc nano xa hoi. ((lieu va) or (hieu va)) cam quoc ban hanh dai cua te*.