Perhaps you should try some spelling variations:
doan dau » doan dieu, phan dau, doan va
te sach » toc sach
sach ky » sac ky, sach y, sach ty
dau cua » dai cua, day cua, cau cua
thuc va » thuc vat, thuc dan, thuc day
hieu su » hieu sau, hieu so, hieu suat
tieu su » thieu so
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
tuc va » truc va, tuc xa, duc va
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky nang ma hoi. ((hieu su) OR (tieu su)) kham ((tuc va) or (thuc va)) doan dau cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang ma hoi. ((hieu su) OR (tieu su)) kham ((tuc va) OR (thuc va)) doan dau cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang ma hoi. ((hieu su) OR (tieu su)) kham ((tuc va) or (thuc va)) doan dau cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang ma hoi. ((hieu su) OR (tieu su)) kham ((tuc va) or (thuc va)) doan dau cua tre*.