Perhaps you should try some spelling variations:
doc sach » hoc sach, nuoc sach, dac sac
toc sach » hoc sach, thuoc sach, nuoc sach
nang mai » nang ma, nang tai, lang mai
hieu van » hieu va, thien van, lieu va
va trien » va truyen, va thiet, va tuyen
mai hoi » mai khoi, dai hoi, lai hoi
van cam » van nam, van lam, van cau
va danh » va dinh, va dan, va hanh
danh ki » danh di, danh kien, danh gia
xuc va » duc va, tuc va, luc va
ki va » khi va, ke va, bi 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 (toc sach)) ky nang mai hoi. hieu van cam xuc va danh ki va trien~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc sach) OR (toc sach)) ky nang mai hoi. hieu van cam xuc va danh ki va trien".
• Adding a wildcard symbol may retrieve word variants: ((doc sach) OR (toc sach)) ky nang mai hoi. hieu van cam xuc va danh ki va trien*.