Perhaps you should try some spelling variations:
sach pham » sach tham, sach phat, sach phap
hieu van » hieu va, thien van, lieu va
thang va » trang va, thong va, thanh va
cau thuc » cau truc, cuu thuc, can thuc
danh vi » dinh vi, danh di, danh va
tu sach » thu sach, su sach, te sach
van cau » van dau, van hau, van chat
cuu tre » cua tre, cau tren, cau treo

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 pham ((thang va) OR (hang va)) hoi. hieu van cau thuc vat ((danh vi) or (hanh vi)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach pham ((thang va) OR (hang va)) hoi. hieu van cau thuc vat ((danh vi) OR (hanh vi)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach pham ((thang va) OR (hang va)) hoi. hieu van cau thuc vat ((danh vi) or (hanh vi)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach pham ((thang va) OR (hang va)) hoi. hieu van cau thuc vat ((danh vi) or (hanh vi)) cuu tre*.