Perhaps you should try some spelling variations:
so triet » su triet, so thiet, bo triet
pham duy » pham duc
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
sach ty » sach tu, sach thu, xach tay
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
ve pham » vi pham, v pham, ve phan
hai so » dai so, tai so, thai son

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) or (sach y)) nang xa hoi. hieu ve pham duy ((van hanh) OR (ban hanh)) hai so triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach y)) nang xa hoi. hieu ve pham duy ((van hanh) OR (ban hanh)) hai so triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) or (sach y)) nang xa hoi. hieu ve pham duy ((van hanh) OR (ban hanh)) hai so triet*".