Perhaps you should try some spelling variations:
dua tren » dung tren
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
cac thu » cach thuc, cac thoi
sach ly » sach y, sach lo, sach ty
hieu ve » hieu va, hieu van
cuu tre » cua tre, cau tren, cau treo
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
thu va » thuc va, thue va, tu va
ve cac » va cac, vien cac

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 ly ((nang xa) OR (lang xa)) hoi. hieu ve cac thu va hanh vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ly ((nang xa) OR (lang xa)) hoi. hieu ve cac thu va hanh vi ((dua tren) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ly ((nang xa) OR (lang xa)) hoi. hieu ve cac thu va hanh vi ((dua tren) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: su sach ly ((nang xa) OR (lang xa)) hoi. hieu ve cac thu va hanh vi ((dua tren) or (cuu tre))*.