Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
hoc sach » hoc sinh, hoc cac, hoc anh
va thanh » gia thanh, ban thanh, va tinh
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
thuc va » thuc vat, thuc dan, thuc day
lang ha » long ha
lang xa » dang xay, lang van
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: ((tu sach) or (hoc sach)) ky ((lang xa) OR (lang ha)) hoi. hieu van nam thuc va thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (hoc sach)) ky ((lang xa) OR (lang ha)) hoi. hieu van nam thuc va thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (hoc sach)) ky ((lang xa) OR (lang ha)) hoi. hieu van nam thuc va thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (hoc sach)) ky ((lang xa) OR (lang ha)) hoi. hieu van nam thuc va thanh dai cua tre*.