Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
dua tren » dung tren
van hanh » van thanh, ban hanh, van anh
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
sach ky » sac ky, sach y, sach ty
su sach » so sach, vu sach
lang xa » lang ha, dang xay, lang van
tang xa » trang xa, tang ma, tang ha
hieu va » lieu va, hieu qua

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 ky ((tang xa) OR (lang xa)) hoi. hieu va cac duc van hanh vi ((dua tren) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((tang xa) OR (lang xa)) hoi. hieu va cac duc van hanh vi ((dua tren) OR (cau tren))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((tang xa) OR (lang xa)) hoi. hieu va cac duc van hanh vi ((dua tren) or (cau tren))*".