Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
dong von » dung von, dong co, dong hoa
dong hoc » dong co, dong luc
cua viet » ca viet, hoa viet, cua vat
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
cach tu » cach thuc

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang mai hoi. hieu qua ((cach tu) or (cac du)) xa ((dong von) OR (dong hoc)) cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang mai hoi. hieu qua ((cach tu) OR (cac du)) xa ((dong von) OR (dong hoc)) cua viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang mai hoi. hieu qua ((cach tu) or (cac du)) xa ((dong von) OR (dong hoc)) cua viet*".