Perhaps you should try some spelling variations:
danh viet » anh viet, ninh viet, nang viet
danh kien » dinh kien, linh kien, van kien
tham duc » pham duc, tham du, than duc
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
tang ma » mang may, tang van
hieu va » lieu va
ty tang » tay tang, ty xang, ty hang
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.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty tang ma hoi. ((hieu va) or (hieu qua)) tham duc va ((danh kien) OR (danh viet)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty tang ma hoi. ((hieu va) OR (hieu qua)) tham duc va ((danh kien) OR (danh viet)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty tang ma hoi. ((hieu va) or (hieu qua)) tham duc va ((danh kien) OR (danh viet)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty tang ma hoi. ((hieu va) or (hieu qua)) tham duc va ((danh kien) OR (danh viet)) cua tre*.