Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh lam » thanh lap, hanh lam, thanh nam
cau tren » cu tren, dau tren, ca tren
hoc sach » hoc sinh, hoc cac, hoc anh
vu pham » su pham, vi pham, vu kham
cua tre » cua te, cuu tre, cua triet
duc van » duc va, duc tan, duc manh
su sach » so sach, vu sach
tang ma » mang may, tang van
ty tang » tay tang, ty xang, ty hang
hieu vu » hieu va, hieu ve, hieu su
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: ((su sach) or (hoc sach)) ty tang ma hoi. hieu vu pham duc van thanh lam ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (hoc sach)) ty tang ma hoi. hieu vu pham duc van thanh lam ((cua tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (hoc sach)) ty tang ma hoi. hieu vu pham duc van thanh lam ((cua tre) or (cau tren))*.