Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
doan hai » doanh tai, hoang hai, doan va
hieu van » hieu va, thien van, lieu va
va triet » va thiet, va trien, ve triet
cam duc » cam xuc, cao duc, pham duc
dan hai » dang hai, dan khai, van hai
van cam » van nam, van lam, van cau
v nang » va nang, vu nang, van nang
y nang » ky nang, ly nang, may 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 ((y nang) or (v nang)) xa hoi. hieu van cam duc va ((dan hai) OR (doan hai)) va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((y nang) OR (v nang)) xa hoi. hieu van cam duc va ((dan hai) OR (doan hai)) va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((y nang) or (v nang)) xa hoi. hieu van cam duc va ((dan hai) OR (doan hai)) va triet".
• Adding a wildcard symbol may retrieve word variants: thu sach ((y nang) or (v nang)) xa hoi. hieu van cam duc va ((dan hai) OR (doan hai)) va triet*.