Perhaps you should try some spelling variations:
doan dau » doan dieu, phan dau, doan va
sach ty » sach y, sach tu, sach thu
dau cua » dai cua, day cua, cau cua
thuc va » thuc vat, thuc dan, thuc day
te sach » toc sach
su kham » su pham, vu kham, so kham
hieu su » hieu sau, tieu su, hieu so
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
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 ty nang ma hoi. hieu 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 ty nang ma hoi. hieu su kham ((tuc va) OR (thuc va)) doan dau cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach ty nang ma hoi. hieu su kham ((tuc va) or (thuc va)) doan dau cua tre*.