Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
thuc van » thuc dan, thuc va, thuc hanh
hieu van » hieu va, thien van, lieu va
van cau » van dau, van hau, van chat
tu sach » thu sach, su sach, te sach
hang ca » hang va, nang cao, hang tai
hang co » hang cho, nang co, lang co
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di 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 thu ((hang co) OR (hang ca)) loi. hieu van cau ((thuc van) or (thuc vat)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu ((hang co) OR (hang ca)) loi. hieu van cau ((thuc van) OR (thuc vat)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thu ((hang co) OR (hang ca)) loi. hieu van cau ((thuc van) or (thuc vat)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach thu ((hang co) OR (hang ca)) loi. hieu van cau ((thuc van) or (thuc vat)) hanh vi cua tre*.