Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
long ha » dong ha, cong ha, dong hoa
sach ky » sac ky, sach y, sach ty
hieu ha » hieu hoa, hieu va, hieu ca
nam tu » nam thu, nam thuc
tu van » tu va
vai su » van su, lai su, tai su

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 ky ((lang ha) OR (long ha)) hoi. hieu ha nam tu van hanh ((vai su) or (va su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((lang ha) OR (long ha)) hoi. hieu ha nam tu van hanh ((vai su) OR (va su)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky ((lang ha) OR (long ha)) hoi. hieu ha nam tu van hanh ((vai su) or (va su)) triet".
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((lang ha) OR (long ha)) hoi. hieu ha nam tu van hanh ((vai su) or (va su)) triet*.