Perhaps you should try some spelling variations:
vien cao » vien cac, vien dai, vien va
thanh va » thanh van, hanh va, thanh ha
va thanh » gia thanh, ban thanh, va tinh
vien da » vien dai, hien dai
su sach » so sach
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
vu sach » vu bach, vu khach
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (vu sach)) ky dang xa hoi. thieu ((vien cao) OR (vien da)) nuoc va thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ky dang xa hoi. thieu ((vien cao) OR (vien da)) nuoc va thanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu sach)) ky dang xa hoi. thieu ((vien cao) OR (vien da)) nuoc va thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) ky dang xa hoi. thieu ((vien cao) OR (vien da)) nuoc va thanh va cua tre*.