Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
xa khanh » xa thanh, van khanh, dat khanh
so sach » so sanh, bo sach, co sach
xa hanh » xa thanh, va hanh, da hanh
sach ky » sac ky, sach y, sach ty
cam thu » nam thu, cac thu, ca thu
van cam » van nam, van lam, van cau
nang xa » lang xa, nang ma, mang xa
so viet » hoc viet
tai so » tai sao, dai so, tai co

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky ((nang xa) or (nang x)) hoi. hieu van cam thu ((xa hanh) OR (xa khanh)) tai so viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky ((nang xa) OR (nang x)) hoi. hieu van cam thu ((xa hanh) OR (xa khanh)) tai so viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky ((nang xa) or (nang x)) hoi. hieu van cam thu ((xa hanh) OR (xa khanh)) tai so viet".
• Adding a wildcard symbol may retrieve word variants: so sach ky ((nang xa) or (nang x)) hoi. hieu van cam thu ((xa hanh) OR (xa khanh)) tai so viet*.