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
duc ban » duc van, dua ban, duc man
cua tre » cua te, cuu tre, cua triet
son hai » cong hai
va cao » va cac, va co, va dao
va cam » va cham, va cac, va cai
anh di » danh di, xanh di, anh d
di cua » dai cua, doi cua, de cua

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 cao)) ((duc ban) OR (duc tan)) anh di 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 cao)) ((duc ban) OR (duc tan)) anh di 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 cao)) ((duc ban) OR (duc tan)) anh di cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang son hai. hieu ((va cam) or (va cao)) ((duc ban) OR (duc tan)) anh di cua tre*.