Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
quoc ban » quoc bao, quoc lan, quoc quan
lanh dai » lanh dao, lanh hai, lang dai
sach ky » sach y, sach ty, sach kem
lang xa » lang ha, dang xay, lang van
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky

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 ky) OR (sac ky)) lang xa hoi. hieu van nam ((quoc ban) or (duc van)) lanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sac ky)) lang xa hoi. hieu van nam ((quoc ban) OR (duc van)) lanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) OR (sac ky)) lang xa hoi. hieu van nam ((quoc ban) or (duc van)) lanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) OR (sac ky)) lang xa hoi. hieu van nam ((quoc ban) or (duc van)) lanh dai cua tre*.