Perhaps you should try some spelling variations:
van pham » san pham, van phan, van phat
su sach » so sach, vu 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
cau duc » cao duc, cau luc, chu duc
va pham » va phat, va phap, va phan
thi cuc » tai cuc
va cau » van cau, va cac, va dau
cuc tu » cuc du, luc tu, duc tu

You may be able to get more results by adjusting your search query.

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