Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
tham soc » cham soc, tham nuoc, thai son
dang xay » dang van, van xay
va hanh » van hanh, va thanh, va danh
hieu va » hieu qua
luu tre » luu tru, cuu tre, luy tre
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
soc va » hoc va, loc va, doc va
vi luu » vi lua

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) or (doc sach)) ky dang xay hoi. ((lieu va) or (hieu va)) tham soc va hanh vi luu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ky dang xay hoi. ((lieu va) OR (hieu va)) tham soc va hanh vi luu tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) ky dang xay hoi. ((lieu va) or (hieu va)) tham soc va hanh vi luu tre*.