Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
hien cac » thien cac, vien cac, hieu cac
hanh vai » hanh vi, hanh tai, hanh van
hanh va » hang va, hanh vi
cac duc » cac du, cao duc, cac dac
su sach » so sach, vu sach
man hoi » man hoai, dan hoi, van hoi
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
cuu tre » cua tre, cau tren, cau treo

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