Perhaps you should try some spelling variations:
su triet » su viet, su tien
nang mai » nang ma, lang mai, nang cai
ve triet » va trien
nang tai » hang tai, tang tai, sang tai
van hanh » van thanh, ban hanh, van anh
cam duc » cam xuc, cao duc, pham duc
hanh ki » hanh vi, hanh ky, hanh kien
duc van » duc va, duc tan, duc manh
tu sach » thu sach, su sach, te sach
sach va » sach xa, sach ha, sach dao
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao

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 va ((nang mai) OR (nang tai)) hoi. hieu va cam duc van hanh ki ((ve triet) or (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach va ((nang mai) OR (nang tai)) hoi. hieu va cam duc van hanh ki ((ve triet) OR (su triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach va ((nang mai) OR (nang tai)) hoi. hieu va cam duc van hanh ki ((ve triet) or (su triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach va ((nang mai) OR (nang tai)) hoi. hieu va cam duc van hanh ki ((ve triet) or (su triet))*.