Perhaps you should try some spelling variations:
thien van » thi van
hanh dan » thanh dan, hanh san, canh dan
dan cua » dan ca, ban cua, dai cua
van lam » van nam
so sach » so sanh, bo sach, co sach
cai hoi » cau hoi, dai hoi, cai hoa
ty hang » ly hang, ty xang, thi hang
ty nang » ky nang, ty xang, ly nang
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, truc va, tuc xa

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((ty nang) OR (ty hang)) cai hoi. thien van lam ((duc va) or (tuc va)) hanh dan cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ty nang) OR (ty hang)) cai hoi. thien van lam ((duc va) OR (tuc va)) hanh dan cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ty nang) OR (ty hang)) cai hoi. thien van lam ((duc va) or (tuc va)) hanh dan cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((ty nang) OR (ty hang)) cai hoi. thien van lam ((duc va) or (tuc va)) hanh dan cua tre*.