Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
va trien » va truyen, va thiet, va tuyen
ban hanh » ban hang
luc ban » duc ban, cuc ban, luc bat
va nang » van nang, da nang, cam nang
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
hieu va » lieu va, hieu qua

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