Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cac nuoc » cap nuoc, dat nuoc, cua nuoc
hieu va » lieu va, hieu qua
te sach » toc sach
vu nang » vuc nang, va nang, vu dang
ma hoi » mai hoi, xa hoi, ma hoa
v nang » va nang, van nang, voi nang
vi cua » vai cua, di cua
cua tu » cua tuc, cua su, cua cu

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