Perhaps you should try some spelling variations:
thien van » thi van
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, lieu va, hieu ve
tham hoc » thai hoc, tham hoa, than hoc
ban hanh » ban hang
cau tren » cu tren, dau tren, ca tren
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
hoc ban » hoc bang, hoc dan, hoc bai
vi cau » va cau, ve cau, di cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ((ky lang) OR (ky dang)) xa hoi. ((hieu van) or (thien van)) tham hoc ban hanh vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ky lang) OR (ky dang)) xa hoi. ((hieu van) OR (thien van)) tham hoc ban hanh vi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky lang) OR (ky dang)) xa hoi. ((hieu van) or (thien van)) tham hoc ban hanh vi cau tren".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky lang) OR (ky dang)) xa hoi. ((hieu van) or (thien van)) tham hoc ban hanh vi cau tren*.