Perhaps you should try some spelling variations:
doan van » doan va, hoang van, luan van
thu sach » tu sach, thuat sach, thuoc sach
thu san » thuy san, thu ban, phu san
hieu va » lieu va, hieu qua
cac lao » ca lao, cac loai, cac giao
va doan » va doanh, van doan, va dan
van cuu » van cau, van chu, van cu
cuu tre » cua tre, cau tren, cau treo
lao va » tao va, cao va, bao va
x hoi » xa hoi, o hoi, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (thu san)) ky nang ((x hoi) OR (x ho)). hieu va cac lao va doan van cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thu san)) ky nang ((x hoi) OR (x ho)). hieu va cac lao va doan van cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thu san)) ky nang ((x hoi) OR (x ho)). hieu va cac lao va doan van cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thu san)) ky nang ((x hoi) OR (x ho)). hieu va cac lao va doan van cuu tre*.