Perhaps you should try some spelling variations:
van pham » san pham, van phan, van phat
nhan tai » van tai, toan tai
hang tai » hang va, dung tai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
va chat » van chat, va phat, cao chat
x hoi » xa hoi, o hoi, x ho
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang x hoi. hieu ((van pham) or (va chat)) duc va ((nhan tai) OR (hang tai)) va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu ((van pham) OR (va chat)) duc va ((nhan tai) OR (hang tai)) va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu ((van pham) or (va chat)) duc va ((nhan tai) OR (hang tai)) va thiet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu ((van pham) or (va chat)) duc va ((nhan tai) OR (hang tai)) va thiet*.