Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su sach » vu sach
dan hai » doan hai, dang hai, dan khai
van cau » van dau, van hau, van chat
nang ma » tang ma, sang ma, nang cao
so sach » so sanh, bo sach, co sach
cu tren » tu tren, dua tren
ma hoi » mai hoi, xa hoi, ma hoa
y nang » ky nang, ly nang, v nang
tuc va » thuc va, truc va, duc va
hai cu » hai cua, hai chu, hai cuc

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 (so sach)) y nang ma hoi. hieu van cau ((tuc va) OR (tuc xa)) dan hai cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) y nang ma hoi. hieu van cau ((tuc va) OR (tuc xa)) dan hai cu tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) y nang ma hoi. hieu van cau ((tuc va) OR (tuc xa)) dan hai cu tren*".