Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
quoc ban » quoc bao, quoc quan, quoc binh
quoc lan » nuoc luan, quoc quan, quoc danh
manh hai » lanh hai, minh hai, thanh hai
sach ky » sac ky, sach y, sach ty
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
van cam » van nam, van lam, van cau
hai cua » thai cua, dai cua, hoi cua
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 ky lang xa hoi. hieu van cam ((((quoc ban) OR (quoc lan))) or (duc va)) manh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky lang xa hoi. hieu van cam ((((quoc ban) OR (quoc lan))) OR (duc va)) manh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky lang xa hoi. hieu van cam ((((quoc ban) OR (quoc lan))) or (duc va)) manh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky lang xa hoi. hieu van cam ((((quoc ban) OR (quoc lan))) or (duc va)) manh hai cua tre*.