Perhaps you should try some spelling variations:
xa thanh » va thanh, ha thanh, ta thanh
cac tac » cac toc, cac bac, cac dac
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
tu sach » thu sach, su sach, te sach
nang co » nang cao, nang doc, nang noi
tac xa » tuc xa, tac da
nang o » nang ho, nang ro, nang x
ve cac » va cac, vien cac
vi su » va su, ve su, oi su
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 ty ((nang o) OR (nang co)) hoi. hieu ve cac tac xa thanh ((vi su) or (ki su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang o) OR (nang co)) hoi. hieu ve cac tac xa thanh ((vi su) OR (ki su)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang o) OR (nang co)) hoi. hieu ve cac tac xa thanh ((vi su) or (ki su)) triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang o) OR (nang co)) hoi. hieu ve cac tac xa thanh ((vi su) or (ki su)) triet*.