Perhaps you should try some spelling variations:
thanh lap » thanh san, phan lap, thanh hai
sach tham » sach nha
hieu van » hieu va, thien van, lieu va
sach thu » sach thue, sach thieu, cach thuc
lap cua » lai cua, tap cua, lam cua
van cam » van nam, van lam, van cau
cao loi » co loi, cao tuoi, ngao loi
xuc va » duc va, tuc va, luc va
cua tu » cua tuc, cua su, cua cu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach thu) OR (sach tham)) nang cao loi. hieu van cam ((xuc va) or (thuc vat)) thanh lap cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach thu) OR (sach tham)) nang cao loi. hieu van cam ((xuc va) OR (thuc vat)) thanh lap cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach thu) OR (sach tham)) nang cao loi. hieu van cam ((xuc va) or (thuc vat)) thanh lap cua tu".
• Adding a wildcard symbol may retrieve word variants: su ((sach thu) OR (sach tham)) nang cao loi. hieu van cam ((xuc va) or (thuc vat)) thanh lap cua tu*.