Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
cong tac » cong ty
va dinh » van dinh, va kinh, va tinh
ly cong » li cong, ky cong, le cong
tac hoi » tao hoi, tay hoi, tac hai
hieu va » lieu va, hieu qua
vai cua » hai cua, lai cua, bai cua
sach ly » sach y, sach lo, sach ty
va hanh » van hanh, va thanh, va danh
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ly cong tac hoi. hieu va cam xuc ((va hanh) or (va dinh)) ((vai cua) OR (dai cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ly cong tac hoi. hieu va cam xuc ((va hanh) OR (va dinh)) ((vai cua) OR (dai cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ly cong tac hoi. hieu va cam xuc ((va hanh) or (va dinh)) ((vai cua) OR (dai cua)) te".
• Adding a wildcard symbol may retrieve word variants: doc sach ly cong tac hoi. hieu va cam xuc ((va hanh) or (va dinh)) ((vai cua) OR (dai cua)) te*.