Perhaps you should try some spelling variations:
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cua triet, dua tren
danh di » danh du, xanh di, danh dien
va danh » va dinh, va dan, va hanh
truc va » thuc va, thuc vat, trung va
tu sach » thu sach, su sach, te sach
van hac » van hoc, van ha, van hai
van bac » van ban, van bao, dan bac
nang ma » tang ma, sang ma, nang cao
cuu tre » cau tren, cau treo
ma hoi » mai hoi, xa hoi, ma hoa

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 ma hoi. hieu ((van bac) or (van hac)) truc va danh di ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. hieu ((van bac) OR (van hac)) truc va danh di ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ma hoi. hieu ((van bac) or (van hac)) truc va danh di ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu ((van bac) or (van hac)) truc va danh di ((cua tre) OR (cuu tre))*.