Perhaps you should try some spelling variations:
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
truc va » thuc va, trung va
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
vi cua » vai cua, di 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) or (su sach)) ky nang ma hoa. hieu ve cac ((truc va) OR (thuc vat)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang ma hoa. hieu ve cac ((truc va) OR (thuc vat)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang ma hoa. hieu ve cac ((truc va) OR (thuc vat)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang ma hoa. hieu ve cac ((truc va) OR (thuc vat)) hanh vi cua tre*.