Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
vu khach » vu khanh, vu khac, vay khach
hieu van » hieu va, thien van, lieu va
cham hoc » chat hoc, cham hoi, cho hoc
nang xa » nang x, lang xa, nang ma
va hanh » van hanh, va thanh, va danh
vi hoa » voi hoa, vi hoc, va hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (vu khach)) ky nang xa hoi. hieu van ((cham hoc) OR (cham soc)) va hanh vi hoa viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc sach) or (vu khach)) ky nang xa hoi. hieu van ((cham hoc) OR (cham soc)) va hanh vi hoa viet~".
• Adding a wildcard symbol may retrieve word variants: ((doc sach) or (vu khach)) ky nang xa hoi. hieu van ((cham hoc) OR (cham soc)) va hanh vi hoa viet*.