Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thanh va » thanh van, hanh va, thanh ha
sach ky » sach y, sach ty, sach kem
tang xa » trang xa, tang ma, lang xa
duoc va » nuoc va, duoc ma, duong va
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
va cua » va chua, via cua, ca cua

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