Perhaps you should try some spelling variations:
luan hoan » luan van
cau tren » cu tren, dau tren, ca tren
ham luan » pham luan, han luan, phap luan
dang va » dang van, dang vat, dung va
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
hieu ve » hieu va, hieu van
ve ham » ve cham, le ham, ve am

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 ty ((nang xa) or (nang ma)) hoi. hieu ve ham luan hoan ((dang va) or (hang va)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang xa) OR (nang ma)) hoi. hieu ve ham luan hoan ((dang va) OR (hang va)) cau tren.
• Adding a wildcard symbol may retrieve word variants: su sach ty ((nang xa) or (nang ma)) hoi. hieu ve ham luan hoan ((dang va) or (hang va)) cau tren*.