Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
van hanh » van thanh, ban hanh, van anh
te sach » toc sach
duc van » duc va, duc tan, duc manh
cam duc » cam xuc, cao duc, pham duc
hieu va » lieu va, hieu qua
ky tang » ky nang, ky dang, kho tang
ky lang » ky nang, ky dang, tay lang
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (thuat sach)) ((ky lang) OR (ky tang)) xa hoi. hieu va cam duc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (thuat sach)) ((ky lang) OR (ky tang)) xa hoi. hieu va cam duc van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (thuat sach)) ((ky lang) OR (ky tang)) xa hoi. hieu va cam duc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (thuat sach)) ((ky lang) OR (ky tang)) xa hoi. hieu va cam duc van hanh vi cua tre*.