Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
thanh tai » thanh hai, thanh toan, doanh tai
dau tren » dau tien, dat tren, dau tieng
nay thuc » nam thuc, cay thuc, day thuc
va thanh » gia thanh, ban thanh, va tinh
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
tai dau » tac dau, tai du, thi dau
tu sach » thu sach, su sach, te sach
va nay » va ngay, va cay
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 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: ((tu sach) or (thuat sach)) ky nang ((x hoi) OR (o hoi)). hieu va nay thuc va thanh tai dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thuat sach)) ky nang ((x hoi) OR (o hoi)). hieu va nay thuc va thanh tai dau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thuat sach)) ky nang ((x hoi) OR (o hoi)). hieu va nay thuc va thanh tai dau tren".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thuat sach)) ky nang ((x hoi) OR (o hoi)). hieu va nay thuc va thanh tai dau tren*.