Perhaps you should try some spelling variations:
sach thi » sach tai, sach thieu, sach tham
sach thu » sach thue, sach thieu, sach tham
nang mai » nang ma, nang tai, lang mai
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va, hieu qua
cao duc » dao duc, cao suc, giao duc
va danh » va dinh, va dan, va hanh
vai cua » hai cua, lai cua, bai cua
va cao » va cac, va co, va dao

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 thi) or (sach thu)) nang mai hoi. hieu va cao duc va danh ((vai cua) OR (dai cua)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach thi) OR (sach thu)) nang mai hoi. hieu va cao duc va danh ((vai cua) OR (dai cua)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach thi) or (sach thu)) nang mai hoi. hieu va cao duc va danh ((vai cua) OR (dai cua)) triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach thi) or (sach thu)) nang mai hoi. hieu va cao duc va danh ((vai cua) OR (dai cua)) triet*.