Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
hieu van » hieu va, thien van, lieu va
cau tren » cu tren, dau tren, ca tren
cua viet » ca viet, hoa viet, cua vat
tu sach » thu sach, su sach, te sach
mai hoi » mai khoi, dai hoi, lai hoi
van cau » van dau, van hau, van chat
truc va » thuc va, trung va
y nang » ky nang, ly nang, v nang

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 hoi. hieu van cau ((truc va) OR (thuc vat)) hanh vi ((cau tren) OR (cua viet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang mai hoi. hieu van cau ((truc va) OR (thuc vat)) hanh vi ((cau tren) or (cua viet))~".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang mai hoi. hieu van cau ((truc va) OR (thuc vat)) hanh vi ((cau tren) or (cua viet))*.