Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hanh vai » hanh vi, hanh va, hanh tai
van hanh » van thanh, ban hanh, van anh
vai cau » va cau, van cau, vai cac
xuc van » duc van, luc van, vuc van
su sach » so sach, vu sach
mai hoi » mai khoi, dai hoi, lai hoi
ky tang » ky nang, ky dang, kho tang
ky sang » ky nang, ky dang, duy sang
ve cac » va cac, vien cac
ve cam » ve cham, va cam, ve cai

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 sang) or (ky tang)) mai hoi. hieu ((ve cam) OR (ve cac)) xuc van hanh vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky sang) OR (ky tang)) mai hoi. hieu ((ve cam) OR (ve cac)) xuc van hanh vai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky sang) or (ky tang)) mai hoi. hieu ((ve cam) OR (ve cac)) xuc van hanh vai cau tren".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky sang) or (ky tang)) mai hoi. hieu ((ve cam) OR (ve cac)) xuc van hanh vai cau tren*.