Perhaps you should try some spelling variations:
vanh dai » van dai, vanh tai, lanh dao
tu sach » thu sach, su sach, te sach
va vanh » va van, va danh, va hanh
ve cham » va cham, ve chat, vu cham
cua tre » cua te, cuu tre, cua triet
mai hoi » mai khoi, dai hoi, lai hoi
vu nang » vuc nang, va nang, vu dang
y nang » ky nang, ly nang, v nang
luc va » duc va, tuc va, loc va
ve cam » ve cac, va cam, ve cai

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 ((y nang) or (vu nang)) mai hoi. hieu ((ve cam) OR (ve cham)) luc va vanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y nang) OR (vu nang)) mai hoi. hieu ((ve cam) OR (ve cham)) luc va vanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) or (vu nang)) mai hoi. hieu ((ve cam) OR (ve cham)) luc va vanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) or (vu nang)) mai hoi. hieu ((ve cam) OR (ve cham)) luc va vanh dai cua tre*.