Perhaps you should try some spelling variations:
doc sach » hoc sach, nuoc sach, dac sac
hanh vai » hanh vi, hanh va, hanh tai
van hanh » van thanh, ban hanh, van anh
cua viet » ca viet, hoa viet, cua vat
toc sach » hoc sach, thuoc sach, nuoc sach
hang ca » hang va, nang cao, hang tai
ty hang » ly hang, ty xang, thi hang
va chat » van chat, va phat, cao chat
luc van » luoc van, luu van, duc van
vai cua » dai cua, hai cua, lai cua
ve chat » van chat
ca hoi » cau hoi, cua hoi, xa hoi

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)) ty hang ca hoi. hieu ((ve chat) or (va chat)) luc van hanh vai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (toc sach)) ty hang ca hoi. hieu ((ve chat) OR (va chat)) luc van hanh vai cua viet.
• Adding a wildcard symbol may retrieve word variants: ((doc sach) or (toc sach)) ty hang ca hoi. hieu ((ve chat) or (va chat)) luc van hanh vai cua viet*.