Perhaps you should try some spelling variations:
thanh van » thanh san, thanh toan, thanh phan
dau tren » dau tien, dat tren, dau tieng
nam thuc » nam thuoc, am thuc, nam thu
va thanh » gia thanh, ban thanh, va tinh
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
van dau » van dao, phan dau
sac ky » cac ky, sai ky
va nam » van nam, ha nam, va nay
tu sac » tu sach, tu cac, tu san
o hoc » mo hoc, so hoc, y hoc
o hoi » co hoi, o hai, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky nang ((((o hoi) or (o hoc))) or (co hoc)). hieu va nam thuc va thanh van dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang ((((o hoi) OR (o hoc))) OR (co hoc)). hieu va nam thuc va thanh van dau tren.
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang ((((o hoi) or (o hoc))) or (co hoc)). hieu va nam thuc va thanh van dau tren*.