Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
va hanh » va thanh, va danh, ban hanh
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
su viet » so viet
ha xuc » hoa xuc, ha duc, chat xuc
va ha » va hoa, va kha, va han

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 xa) OR (nang ma)) hoi. hieu va ha xuc ((va hanh) or (van hanh)) lai su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang xa) OR (nang ma)) hoi. hieu va ha xuc ((va hanh) OR (van hanh)) lai su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang xa) OR (nang ma)) hoi. hieu va ha xuc ((va hanh) or (van hanh)) lai su viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang xa) OR (nang ma)) hoi. hieu va ha xuc ((va hanh) or (van hanh)) lai su viet*.