Perhaps you should try some spelling variations:
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
hieu van » hieu va, thien van, lieu va
dua tren » dung tren
tu sach » thu sach, su sach, te sach
hieu ve » hieu va
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
y nang » ky nang, ly nang, v nang
vi dua » vi du, vi dum, vi lua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y nang x ho. ((hieu ve) or (hieu van)) cac nuoc va danh vi dua tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang x ho. ((hieu ve) OR (hieu van)) cac nuoc va danh vi dua tren.
• Adding a wildcard symbol may retrieve word variants: tu sach y nang x ho. ((hieu ve) or (hieu van)) cac nuoc va danh vi dua tren*.