Perhaps you should try some spelling variations:
sanh tri » thanh tri, dinh tri, minh tri
tue cach » tu cach, thuc cach, ve cach
cach hoa » cach hoan, cach hoc, bach hoa
he trong » he thong, he trung, le trong
sach thi » sach thu, sach tai, sach thieu
so sanh » do sanh
so sach » bo sach, co sach, hoc sach
thi thi » thi thai, thi thin, thi thu
anh ha » anh ta, anh ma, anh khoa
anh va » hanh va

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( so sanh tri tue cach hoa he trong ) or ( so sach thi thi ((anh ha) OR (anh va)) he trong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so sanh tri tue cach hoa he trong ) OR ( so sach thi thi ((anh ha) OR (anh va)) he trong )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( so sanh tri tue cach hoa he trong ) or ( so sach thi thi ((anh ha) OR (anh va)) he trong ))".
• Adding a wildcard symbol may retrieve word variants: (( so sanh tri tue cach hoa he trong ) or ( so sach thi thi ((anh ha) OR (anh va)) he trong ))*.