Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
hanh via » hanh vi, hanh va, anh va
van hanh » van thanh, ban hanh, van anh
phan duc » phan tu, phan dau, tran duc
te sach » toc sach
via cua » gia cua, gian cua, giau cua
hieu ve » hieu va, hieu van
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (doc sach)) ky sang ma hoi. hieu ve ((phan duc) OR (pham duc)) van hanh via cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (doc sach)) ky sang ma hoi. hieu ve ((phan duc) OR (pham duc)) van hanh via cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (doc sach)) ky sang ma hoi. hieu ve ((phan duc) OR (pham duc)) van hanh via cua tre*".