Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thu sach » thuat sach, thuoc sach, thu hoach
nang mai » nang ma, nang tai, lang mai
hanh ki » hanh vi, hanh ky, hanh kien
luc van » luoc van, luu van, duc van
xuc van » duc van, vuc van, xuc ban
tu sach » su sach, te sach, tu cach
mai hoi » mai khoi, dai hoi, lai hoi
vu nang » vuc nang, va nang, vu dang
hieu va » lieu va, hieu qua
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) OR (thu sach)) vu nang mai hoi. hieu va cam ((xuc van) or (luc van)) hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) vu nang mai hoi. hieu va cam ((xuc van) OR (luc van)) hanh ki su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) vu nang mai hoi. hieu va cam ((xuc van) or (luc van)) hanh ki su triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) vu nang mai hoi. hieu va cam ((xuc van) or (luc van)) hanh ki su triet*.