Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
cam tuc » cam xuc, cam tu, nam thuc
hieu va » hieu qua
mai hoi » mai khoi, dai hoi, lai hoi
ty hang » ly hang, ty xang, thi hang
ty tang » tay tang, ty xang, ky tang
su viet » so viet
tuc va » thuc va, truc va, tuc xa
tai su » tai so, tai tu, lai 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 ((ty tang) OR (ty hang)) mai hoi. ((hieu va) or (lieu va)) cam tuc va hanh tai su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty tang) OR (ty hang)) mai hoi. ((hieu va) OR (lieu va)) cam tuc va hanh tai su viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty tang) OR (ty hang)) mai hoi. ((hieu va) or (lieu va)) cam tuc va hanh tai su viet*".