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

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 dan hai ((cau tren) OR (dau 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 dan hai ((cau tren) OR (dau 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 dan hai ((cau tren) OR (dau tren))*".