Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
nang cau » nang cao, hang cau, nang dau
nam luc » nang luc, nhan luc, nam thuc
tai cua » thai cua, tai cuc, tri cua
va hanh » va thanh, va danh, ban hanh
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
va nam » van nam, ha nam, va nay

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ky) OR (sach ty)) nang cau hoi. lieu va nam luc ((va hanh) or (van hanh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) nang cau hoi. lieu va nam luc ((va hanh) OR (van hanh)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) OR (sach ty)) nang cau hoi. lieu va nam luc ((va hanh) or (van hanh)) tai cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) OR (sach ty)) nang cau hoi. lieu va nam luc ((va hanh) or (van hanh)) tai cua tre*.