Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
lang mai » lang dai, lang hai, lang man
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
nang mai » nang ma, nang tai, nang cai
van cau » van dau, van hau, van chat
truc va » thuc va, thuc vat, trung va
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
tu sach » thu sach, su sach, te sach

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang mai) OR (lang mai)) hoi. hieu van cau truc va danh vi ((cau tren) OR (cua viet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang mai) OR (lang mai)) hoi. hieu van cau truc va danh vi ((cau tren) or (cua viet))~".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang mai) OR (lang mai)) hoi. hieu van cau truc va danh vi ((cau tren) or (cua viet))*.