Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
cuc nang » chuc nang, cuu nang, cua nang
vuc nang » vu nang, chuc nang, van nang
hieu va » lieu va, hieu qua
xuc van » luc van, vuc van, xuc ban
duc van » duc va, duc tan, duc manh
hanh ki » hanh vi, hanh ky, hanh kien
tu sach » thu sach, su sach, te sach
ma hoi » mai hoi, xa hoi, ma hoa
va cam » va cham, va cac, va cao
ki su » ky su

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 ((vuc nang) OR (cuc nang)) ma hoi. hieu va cam ((xuc van) or (duc van)) hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((vuc nang) OR (cuc nang)) ma hoi. hieu va cam ((xuc van) OR (duc van)) hanh ki su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((vuc nang) OR (cuc nang)) ma hoi. hieu va cam ((xuc van) or (duc van)) hanh ki su triet*".