Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hanh doi » thanh doi, hanh noi, hang doi
van hanh » van thanh, ban hanh, van anh
hieu van » thien van, lieu va, hieu ve
hieu va » lieu va, hieu qua
doi cua » dai cua, hoi cua
luu van » cuu van, luan van, luu hanh
cau luu » cau luc
cua tre » cua te, cuu tre, cua triet
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
tu sach » su sach, te sach, tu cach

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (tu sach)) ky dang xa hoi. ((hieu van) OR (hieu va)) cau luu van hanh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) ky dang xa hoi. ((hieu van) OR (hieu va)) cau luu van hanh doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (tu sach)) ky dang xa hoi. ((hieu van) OR (hieu va)) cau luu van hanh doi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (tu sach)) ky dang xa hoi. ((hieu van) OR (hieu va)) cau luu van hanh doi cua tre*.