Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
ky dang » ky nang, ky danh
dang xa » dang xay, lang xa, dang ha
hieu ve » hieu va, hieu van
luc van » luoc van, luu van, luc va
duc van » duc va, duc tan, duc manh
cuu tre » cua tre, cau tren, cau treo
ve cau » ke cau, va cau, ve cac
vi cuu » vi luu, vinh cuu

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 (thu hoach)) ky dang xa hoi. hieu ve cau ((luc van) OR (duc van)) hanh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thu hoach)) ky dang xa hoi. hieu ve cau ((luc van) OR (duc van)) hanh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thu hoach)) ky dang xa hoi. hieu ve cau ((luc van) OR (duc van)) hanh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thu hoach)) ky dang xa hoi. hieu ve cau ((luc van) OR (duc van)) hanh vi cuu tre*.