Perhaps you should try some spelling variations:
thien van » thi van
hanh tai » thanh tai, hang tai, han tai
mai khoi » mai khoa, tai khoa, cac khoi
cuc tre » duc tre, cuu tre, cuc thue
va hanh » van hanh, va thanh, va danh
cam duc » cam xuc, cao duc, pham duc
van cam » van nam, van lam, van cau
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
mai hoi » dai hoi, lai hoi, mai doi
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet

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 dang ((mai hoi) or (mai khoi)). thien van cam duc va hanh tai ((cuc tre) OR (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang ((mai hoi) OR (mai khoi)). thien van cam duc va hanh tai ((cuc tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang ((mai hoi) or (mai khoi)). thien van cam duc va hanh tai ((cuc tre) OR (cua tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky dang ((mai hoi) or (mai khoi)). thien van cam duc va hanh tai ((cuc tre) OR (cua tre))*.