Perhaps you should try some spelling variations:
hieu viec » nhieu viec, hieu ve, sieu viet
viec cac » vien cac, viec cua, viec lam
van danh » van doanh, van anh, van hanh
danh vai » danh sai, danh va, doanh van
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma
vai cau » va cau, van cau, vai cac
cac vo » cac co, cac vi, cac bo

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 ky ((((nang ma) OR (mang may))) or (nang cao)) hoi. hieu viec cac vo van danh vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((((nang ma) OR (mang may))) OR (nang cao)) hoi. hieu viec cac vo van danh vai cau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((((nang ma) OR (mang may))) or (nang cao)) hoi. hieu viec cac vo van danh vai cau tren*".