Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
doan dau » doan dieu, phan dau, doan va
dau cua » dai cua, day cua, cau cua
thuc va » thuc vat, thuc dan, thuc day
su kham » su pham, vu kham, so kham
nang ma » tang ma, sang ma, nang cao
hieu su » hieu sau, tieu su, hieu so
tuc va » truc va, tuc xa, duc va
ma hoi » mai hoi, xa hoi, ma hoa
cua te » cua tu

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