Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
su triet » su viet, su tien, ve triet
sach thi » sach thu, sach tai, sach thieu
hanh tai » hang tai, han tai, hinh tai
cam tuc » cam xuc, cam tu, nam thuc
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
nang ca » nang cap, nang cai, nang can
tuc va » thuc va, truc va, tuc xa
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 thi ((nang ca) OR (nang cao)) hoi. hieu va cam tuc va ((hanh tai) or (thanh tai)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thi ((nang ca) OR (nang cao)) hoi. hieu va cam tuc va ((hanh tai) OR (thanh tai)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thi ((nang ca) OR (nang cao)) hoi. hieu va cam tuc va ((hanh tai) or (thanh tai)) su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach thi ((nang ca) OR (nang cao)) hoi. hieu va cam tuc va ((hanh tai) or (thanh tai)) su triet*.