Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
tham soc » cham soc, tham nuoc, thai son
cau tren » cu tren, dau tren, ca tren
dang xay » dang van, van xay
xay hoi » xa hoi, tay hoi, cay phoi
hieu va » hieu qua
va hanh » van hanh, va thanh, va danh
cuu tre » cua tre, cau treo
y dang » ky dang, 2 dang, _ dang
soc va » hoc va, loc va, doc va

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 y dang xay hoi. ((lieu va) or (hieu va)) tham soc va hanh vi ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y dang xay hoi. ((lieu va) OR (hieu va)) tham soc va hanh vi ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y dang xay hoi. ((lieu va) or (hieu va)) tham soc va hanh vi ((cuu tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: toc sach y dang xay hoi. ((lieu va) or (hieu va)) tham soc va hanh vi ((cuu tre) OR (cau tren))*.