Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thu sach » tu sach, thuat sach, thu hoach
van hang » van khang, van hoang, van thang
va trien » va truyen, va thiet, va tuyen
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
duc van » duc va, duc tan, duc manh
hang di » hang doi, hang vi, hang dien
cua tre » cua te, cuu tre, cua triet
va pham » van pham, va phat, va phap
v nang » va nang, vu nang, van nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (thuoc sach)) v nang xa hoi. hieu va pham duc van hang di ((cua tre) or (va trien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuoc sach)) v nang xa hoi. hieu va pham duc van hang di ((cua tre) OR (va trien)).
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuoc sach)) v nang xa hoi. hieu va pham duc van hang di ((cua tre) or (va trien))*.