Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
danh hai » dang hai, lanh hai, manh hai
thuc dan » thuc hanh, hoc dan, thuc vat
hieu van » hieu va, thien van, lieu va
vang ma » tang ma, nang ma, sang ma
ly vang » ly hang, ly van, ly quang
van lam » van nam
so sach » so sanh, bo sach, co sach
hai cau » hai chau, hai chu, hai hau
su sach » vu sach
ma hoi » mai hoi, xa hoi, ma hoa

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)) ly vang ma hoi. hieu van lam ((tuc xa) or (thuc dan)) danh hai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ly vang ma hoi. hieu van lam ((tuc xa) OR (thuc dan)) danh hai cau tren.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) ly vang ma hoi. hieu van lam ((tuc xa) or (thuc dan)) danh hai cau tren*.