Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
sach ty » sach y, sach tu, sach thu
hanh ve » hanh va, hanh kem
su sach » so sach, vu sach
ty nang » ky nang, ty xang, ty hang
ve cao » va cao, ve bao, ve co
ve cac » va cac, vien cac
x hoi » xa hoi, o hoi, x ho

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