Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
phat duc » pham duc, phan duc, phan duoc
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
va danh » va dinh, va dan, va hanh
danh di » danh du, xanh di, danh dien
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
di cua » dai cua, doi cua, de cua

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 va phat duc va danh di cua tre~.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky nang ma hoi. hieu va phat duc va danh di cua tre*.