Perhaps you should try some spelling variations:
hieu hieu » hien hieu, hieu hien, thien hieu
hieu cac » hieu luc, hieu va, hieu van
thu sach » tu sach, thuat sach, thuoc sach
mai hoi » mai khoi, dai hoi, lai hoi
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
hanh di » hanh vi, hanh de, hang di
ma hoi » xa hoi, ma hoa, me hoi
loc va » hoc va, luc va
di hoa » dai hoa, doi hoa, do hoa

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

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