Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
cau tren » cu tren, dau tren, ca tren
hanh tai » thanh tai, hang tai, han tai
cac cuc » cac cuoc, cac cua, cac nuoc
cuc ban » cua ban, cac ban, cuu ban
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ma hoi » xa hoi, ma hoa, me hoi
ve cac » va cac, vien cac

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 hoi) OR (mai hoi)). hieu ve cac cuc ban ((thanh hai) or (hanh tai)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((ma hoi) OR (mai hoi)). hieu ve cac cuc ban ((thanh hai) OR (hanh tai)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((ma hoi) OR (mai hoi)). hieu ve cac cuc ban ((thanh hai) or (hanh tai)) cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((ma hoi) OR (mai hoi)). hieu ve cac cuc ban ((thanh hai) or (hanh tai)) cau tren*.