Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nuoc van » nuoc va, nuoc san, luoc van
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
te sach » toc sach
hanh di » hanh de, hang di, danh di
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang

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