Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
doan day » doan dau, doan hay, dan day
vu kham » vu khanh
day cua » dai cua
va doan » va doanh, van doan, va dan
thuc va » thuc vat, thuc dan, thuc day
vu pham » su pham, vi pham, v pham
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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

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