Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
tu sach » su sach, te sach, tu cach
va hanh » van hanh, va thanh, va danh
cac loc » cac lop, cac toc, cac hoc
hieu ve » hieu va, hieu van
ky tang » ky nang, ky dang, kho tang
ky sang » ky nang, ky dang, duy sang
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
loc va » hoc va, luc va
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 (thu sach)) ((ky sang) OR (ky tang)) ma hoa. hieu ve cac loc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ((ky sang) OR (ky tang)) ma hoa. hieu ve cac loc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ((ky sang) OR (ky tang)) ma hoa. hieu ve cac loc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ((ky sang) OR (ky tang)) ma hoa. hieu ve cac loc va hanh vi cua tre*.