Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hien hanh » dieu hanh
danh dau » lanh dao, hang dau, danh tu
duoc va » nuoc va, duc va, duoc ma
dau cua » dai cua, day cua, cau cua
su sach » so sach, vu sach
tuoc va » thuoc va, nuoc va, tuc va
ky lang » ky dang, ky tang, tay lang
cua tre » cua te, cuu tre, cua triet

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 ((ky lang) OR (ky nang)) xa hoi. hieu hien hanh ((tuoc va) or (duoc va)) danh dau cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky lang) OR (ky nang)) xa hoi. hieu hien hanh ((tuoc va) OR (duoc va)) danh dau cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky lang) OR (ky nang)) xa hoi. hieu hien hanh ((tuoc va) or (duoc va)) danh dau cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky lang) OR (ky nang)) xa hoi. hieu hien hanh ((tuoc va) or (duoc va)) danh dau cua tre*.