Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
tu sach » thu sach, su sach, te sach
tai cuu » tai cuc, tai buu, tai cua
va hanh » van hanh, va thanh, va danh
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau tren, cau treo
dai hoi » dai hoc, dai hai, dai moi
hai hoi » hai moi, hai hai, hai hoa
ky lang » ky nang, ky dang, ky tang
va cam » va cham, va cac, va cao
luc va » duc va, tuc va, loc va
ve cam » ve cham, ve cac, 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 ky lang ((hai hoi) OR (dai hoi)). hieu ((ve cam) or (va cam)) luc va hanh tai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang ((hai hoi) OR (dai hoi)). hieu ((ve cam) OR (va cam)) luc va hanh tai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky lang ((hai hoi) OR (dai hoi)). hieu ((ve cam) or (va cam)) luc va hanh tai cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang ((hai hoi) OR (dai hoi)). hieu ((ve cam) or (va cam)) luc va hanh tai cuu tre*.