Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
cua viet » ca viet, cua vat, cua dieu
hien cac » thien cac, vien cac, hieu cac
va hanh » van hanh, va thanh, va danh
cac xuc » cam xuc, cac nuoc, chat xuc
tu sach » thu sach, su sach, te sach
dai hoi » dai hoc, dai hai, dai moi
mai hoi » mai khoi, lai hoi, mai doi
xuc va » duc va, tuc va, luc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach thu nang ((mai hoi) or (dai hoi)). hieu hien cac xuc va hanh vi ((cua viet) or (hoa viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu nang ((mai hoi) OR (dai hoi)). hieu hien cac xuc va hanh vi ((cua viet) OR (hoa viet)).
• Adding a wildcard symbol may retrieve word variants: tu sach thu nang ((mai hoi) or (dai hoi)). hieu hien cac xuc va hanh vi ((cua viet) or (hoa viet))*.