Perhaps you should try some spelling variations:
pham tai » pham thi, pham van
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
duc van » duc va, duc manh, duc phan
tai duc » tai cuc, mai duc, tai du
va cau » van cau, va cac, va dau
duc tu » luc tu

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 ky ((nang xa) or (lang xa)) hoi. hieu va cau ((duc van) OR (duc tan)) pham tai duc tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (lang xa)) hoi. hieu va cau ((duc van) OR (duc tan)) pham tai duc tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) or (lang xa)) hoi. hieu va cau ((duc van) OR (duc tan)) pham tai duc tu".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (lang xa)) hoi. hieu va cau ((duc van) OR (duc tan)) pham tai duc tu*.