Perhaps you should try some spelling variations:
thien van » thi van
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, lieu va, hieu ve
dinh dai » dinh dat, sinh dai, dinh dao
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
chao tu » chao xu, cho tu, cao tu
va dinh » van dinh, va kinh, va tinh
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach y ((nang xa) OR (nang ma)) hoi. ((hieu van) or (thien van)) chao tu va dinh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y ((nang xa) OR (nang ma)) hoi. ((hieu van) OR (thien van)) chao tu va dinh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y ((nang xa) OR (nang ma)) hoi. ((hieu van) or (thien van)) chao tu va dinh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach y ((nang xa) OR (nang ma)) hoi. ((hieu van) or (thien van)) chao tu va dinh dai cua tre*.