Perhaps you should try some spelling variations:
hieu hien » bieu hien, dieu hien, chieu chien
tang hanh » tang thanh, dang hanh, nang hanh
hoc sach » hoc sinh, hoc cac, hoc anh
cac thoi » cac toi, cac tro, cac thu
toc sac » toc sach, toc san, doc sach
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet
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: ((toc sac) OR (hoc sach)) ky dang xa hoi. hieu hien ((cac thoi) or (cac hop)) tang hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sac) OR (hoc sach)) ky dang xa hoi. hieu hien ((cac thoi) OR (cac hop)) tang hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sac) OR (hoc sach)) ky dang xa hoi. hieu hien ((cac thoi) or (cac hop)) tang hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sac) OR (hoc sach)) ky dang xa hoi. hieu hien ((cac thoi) or (cac hop)) tang hanh vi cua tre*.