Perhaps you should try some spelling variations:
doc sach » toc sach, nuoc sach, dac sac
va trien » va truyen, va thiet, va tuyen
hoc sach » hoc sinh, hoc cac, hoc anh
nang xa » nang x, lang xa, nang ma
cam duc » cam xuc, cao duc, pham duc
va hanh » van hanh, va thanh, va danh
hanh de » hanh ve, hanh kem
hieu va » hieu qua
2 nang » v nang
de va » de van, te va, ke va

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) OR (hoc sach)) 2 nang xa hoi. ((hieu va) or (lieu va)) cam duc va hanh de va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (hoc sach)) 2 nang xa hoi. ((hieu va) OR (lieu va)) cam duc va hanh de va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc sach) OR (hoc sach)) 2 nang xa hoi. ((hieu va) or (lieu va)) cam duc va hanh de va trien".
• Adding a wildcard symbol may retrieve word variants: ((doc sach) OR (hoc sach)) 2 nang xa hoi. ((hieu va) or (lieu va)) cam duc va hanh de va trien*.