Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
danh viet » anh viet, ninh viet, nang viet
danh kien » dinh kien, linh kien, van kien
thuc han » thuc hanh, thuc chan, thuc huan
doc sac » doc sach, dac sac, hoc sach
hieu va » hieu qua
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sac ky nang xa hoi. ((hieu va) or (lieu va)) tham thuc han ((danh kien) OR (danh viet)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sac ky nang xa hoi. ((hieu va) OR (lieu va)) tham thuc han ((danh kien) OR (danh viet)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sac ky nang xa hoi. ((hieu va) or (lieu va)) tham thuc han ((danh kien) OR (danh viet)) cua tre".
• Adding a wildcard symbol may retrieve word variants: doc sac ky nang xa hoi. ((hieu va) or (lieu va)) tham thuc han ((danh kien) OR (danh viet)) cua tre*.