Perhaps you should try some spelling variations:
dung tren » dung trong, dung trung
nang tai » hang tai, tang tai, sang tai
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
nuoc van » nuoc va, nuoc san, luoc van
van hanh » van thanh, ban hanh, van anh
cau tren » cu tren, dau tren, ca tren
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
tai hoi » tai khoi, dai hoi, tai hai
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang tai hoi. hieu va cac nuoc van hanh vi ((dung tren) or (((cua tre) or (cau tren))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang tai hoi. hieu va cac nuoc van hanh vi ((dung tren) OR (((cua tre) OR (cau tren)))).
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang tai hoi. hieu va cac nuoc van hanh vi ((dung tren) or (((cua tre) or (cau tren))))*.