Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
tinh cao » tinh lao, tinh chat, tinh cach
thuc day » thuc dan, thuc vat
thuoc va » thuc va, thuoc ma, thuong va
sach thu » sach thue, sach thieu, sach tham
thu sach » tu sach, thuat sach, thuoc sach
tang ma » mang may, tang van
cao cua » ca cua, co cua, cau 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 thu ((tang ma) or (nang x)) hoi. hieu van nam ((thuoc va) or (thuc day)) tinh cao cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach thu ((tang ma) OR (nang x)) hoi. hieu van nam ((thuoc va) OR (thuc day)) tinh cao cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach thu ((tang ma) or (nang x)) hoi. hieu van nam ((thuoc va) or (thuc day)) tinh cao cua tre*.