Perhaps you should try some spelling variations:
thanh dat » thanh san, thanh hai, thanh van
cua tre » cua te, cuu tre, cua triet
dat cua » dai cua, day cua, mat cua
duc ban » duc van, dua ban, duc man
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ky tang » ky nang, ky dang, kho tang
sac ky » cac ky, sai ky
ve cam » ve cham, ve cac, va cam
ma hoi » xa hoi, ma hoa, me hoi
su sac » su sach, su cac, su xac

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sac ky tang ((ma hoi) or (mai hoi)). hieu ve cam ((duc ban) OR (duc tan)) thanh dat cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ky tang ((ma hoi) OR (mai hoi)). hieu ve cam ((duc ban) OR (duc tan)) thanh dat cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sac ky tang ((ma hoi) or (mai hoi)). hieu ve cam ((duc ban) OR (duc tan)) thanh dat cua tre".
• Adding a wildcard symbol may retrieve word variants: su sac ky tang ((ma hoi) or (mai hoi)). hieu ve cam ((duc ban) OR (duc tan)) thanh dat cua tre*.