Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
tu sach » thu sach, su sach, te sach
hanh ky » hanh kem
hanh ki » hanh vi, hanh kien, thanh kim
duc van » duc va, duc tan, duc manh
hieu va » lieu va, hieu qua
va pham » van pham, va phat, va phap
su viet » so viet
ma hoi » mai hoi, ma hoa, me hoi

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 ((ma hoi) or (xa hoi)). hieu va pham duc van ((hanh ki) or (hanh ky)) su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu nang ((ma hoi) OR (xa hoi)). hieu va pham duc van ((hanh ki) OR (hanh ky)) su viet.
• Adding a wildcard symbol may retrieve word variants: tu sach thu nang ((ma hoi) or (xa hoi)). hieu va pham duc van ((hanh ki) or (hanh ky)) su viet*.