Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
xanh doi » xanh di, thanh doi, tinh doi
vat xanh » vat thanh, sat anh, dat anh
van hac » van hoc, van ha, van hai
doi cua » dai cua, hoi cua
tu sach » su sach, te sach, tu cach
van bac » van ban, van bao, dan bac
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
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) OR (thu sach)) ky nang ma hoi. hieu ((van bac) or (van hac)) thuc vat xanh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang ma hoi. hieu ((van bac) OR (van hac)) thuc vat xanh doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) ky nang ma hoi. hieu ((van bac) or (van hac)) thuc vat xanh doi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) ky nang ma hoi. hieu ((van bac) or (van hac)) thuc vat xanh doi cua tre*.