Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
va hanh » van hanh, va thanh, va danh
cac luc » cau luc, coc luc, cac nuoc
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
nang ma » tang ma, nang cao, mang may
vu sach » vu bach, su sach, vu khach
sang ma » tang ma, sang tao, mang may
luc va » duc va, tuc va, loc va
vi va » vi van, vai va, vu va

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) or (vu sach)) ky ((nang ma) OR (sang ma)) hoi. hieu va cac luc va hanh vi va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (vu sach)) ky ((nang ma) OR (sang ma)) hoi. hieu va cac luc va hanh vi va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (vu sach)) ky ((nang ma) OR (sang ma)) hoi. hieu va cac luc va hanh vi va triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (vu sach)) ky ((nang ma) OR (sang ma)) hoi. hieu va cac luc va hanh vi va triet*.