Perhaps you should try some spelling variations:
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
sach thu » sach thue, sach thieu, sach tham
so sach » so sanh, bo sach, co sach
hieu su » hieu sau, tieu su, hieu so
sang ma » tang ma, nang ma, sang tao
lang ha » long ha
cua tre » cua te, cuu tre, cua triet
su ham » su pham, su hai, su nam
ham so » nam so, cham soc
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: so sach thu ((sang ma) or (lang ha)) hoi. hieu su ham so ((van hanh) OR (ban hanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach thu ((sang ma) OR (lang ha)) hoi. hieu su ham so ((van hanh) OR (ban hanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach thu ((sang ma) or (lang ha)) hoi. hieu su ham so ((van hanh) OR (ban hanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach thu ((sang ma) or (lang ha)) hoi. hieu su ham so ((van hanh) OR (ban hanh)) vi cua tre*.