Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hanh van » thanh van, khanh van, hanh va
van cau » van dau, van hau, van chat
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
mai hoi » mai khoi, dai hoi, lai hoi
ty nang » ky nang, ty xang, ty hang
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam
xac va » tac va, ac va, bac va
ma hoi » xa hoi, ma hoa, me hoi

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