Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
doi cua » dai cua, hoi cua
va xanh » va danh, va hanh, va anh
truc va » thuc va, thuc vat, trung va
van hac » van hoc, van ha, van hai
sach ky » sac ky, sach y, sach ty
van bac » van ban, van bao, dan bac
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
di cua » dai cua, de cua, do 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 ma hoi. hieu ((van bac) or (van hac)) truc va xanh ((di cua) OR (doi cua)) 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 xanh ((di cua) OR (doi cua)) 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 xanh ((di cua) OR (doi cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu ((van bac) or (van hac)) truc va xanh ((di cua) OR (doi cua)) tre*.