Perhaps you should try some spelling variations:
quoc ban » quoc bao, quoc lan, quoc quan
nuoc ban » nuoc san, buoc ban, duoc ban
te sach » toc sach
hieu ve » hieu va, hieu van
cua tuc » cua duc, cua tu, cua thuoc
ma hoi » mai hoi, xa hoi, ma hoa
ve cac » va cac, vien cac
5 tang » 6 tang, 7 tang
v tang » 6 tang, 7 tang, 9 tang
vi cua » vai cua, di cua

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 ((v tang) or (5 tang)) ma hoi. hieu ve cac ((nuoc ban) OR (quoc ban)) hanh vi cua tuc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((v tang) OR (5 tang)) ma hoi. hieu ve cac ((nuoc ban) OR (quoc ban)) hanh vi cua tuc.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((v tang) or (5 tang)) ma hoi. hieu ve cac ((nuoc ban) OR (quoc ban)) hanh vi cua tuc".
• Adding a wildcard symbol may retrieve word variants: te sach ((v tang) or (5 tang)) ma hoi. hieu ve cac ((nuoc ban) OR (quoc ban)) hanh vi cua tuc*.