Perhaps you should try some spelling variations:
nang son » nang song, nang soan, lang son
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
son hai » cong hai
duc ban » duc tan, duc van, dua ban
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cao, va cai
anh di » danh di, xanh di, anh du

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 nang son hai. hieu ((va cam) or (va cac)) duc ban ((anh di) OR (anh d)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang son hai. hieu ((va cam) OR (va cac)) duc ban ((anh di) OR (anh d)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang son hai. hieu ((va cam) or (va cac)) duc ban ((anh di) OR (anh d)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang son hai. hieu ((va cam) or (va cac)) duc ban ((anh di) OR (anh d)) cua tre*.