Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
va trien » va truyen, va thiet, va tuyen
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
qua cam » qua cham, qua cac, qua ca
xuc van » duc van, luc van, vuc van
kem va » kiem va, kiem van

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 (toc sach)) ky tang xa hoi. hieu qua cam xuc van hanh kem va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky tang xa hoi. hieu qua cam xuc van hanh kem va trien.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky tang xa hoi. hieu qua cam xuc van hanh kem va trien*.