Perhaps you should try some spelling variations:
su triet » su viet, ve triet
thanh vi » hanh vi, thanh va, thanh ve
xa thanh » va thanh, ha thanh, ta thanh
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
cac tac » cac toc, cac bac, cac dac
hieu ve » hieu va, hieu van
su tien » su kien, su hien, tu tieng
ve cac » va cac, vien cac
tac xa » tuc xa, tac da
tang o » trang o, lang o
xang o » lang o, dang o

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 ((xang o) OR (tang o)) hoi. hieu ve cac tac xa thanh vi ((su triet) or (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((xang o) OR (tang o)) hoi. hieu ve cac tac xa thanh vi ((su triet) OR (su tien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((xang o) OR (tang o)) hoi. hieu ve cac tac xa thanh vi ((su triet) or (su tien))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((xang o) OR (tang o)) hoi. hieu ve cac tac xa thanh vi ((su triet) or (su tien))*.