Perhaps you should try some spelling variations:
truc ngan » tu ngan, thu ngan, tri ngan
dua tren » dung tren
tu sach » thu sach, su sach, te sach
sach ly » sach y, sach lo, sach ty
ly hang » ly quang
hang xa » hoang xa, hang va, hang ca
hieu va » lieu va, hieu qua
hang vi » hang va, hanh vi, hang di
co tren » cu tren, do tren, ca tren
va cau » van cau, va cac, va dau

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ly hang xa hoi. hieu va cau truc ngan hang vi ((co tren) or (dua tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ly hang xa hoi. hieu va cau truc ngan hang vi ((co tren) OR (dua tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach ly hang xa hoi. hieu va cau truc ngan hang vi ((co tren) or (dua tren))*.