Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
phat duc » pham duc, phan duc, phan duoc
danh du » danh dau, danh tu, dinh du
danh di » xanh di, danh dien, danh gia
hieu va » lieu va, hieu qua
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 va phat duc va ((danh di) OR (danh du)) 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 va phat duc va ((danh di) OR (danh du)) 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) OR (danh du)) cua tre*.