Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hang hai » hoang hai, hang tai, thanh hai
va triet » va thiet, va trien, ve triet
nang ma » tang ma, sang ma, nang cao
va pham » van pham, va phat, va phap
va hang » van hang, va nang, va lang
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa
hai va » hai van, thai va, hoi va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (dac sac)) y nang ma hoi. lieu va pham duc va hang hai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (dac sac)) y nang ma hoi. lieu va pham duc va hang hai va triet.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (dac sac)) y nang ma hoi. lieu va pham duc va hang hai va triet*.