Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
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
mai hoi » mai khoi, dai hoi, lai hoi
van cau » van dau, van hau, van chat
truc va » thuc va, thuc vat, trung va
va hanh » van hanh, va thanh, va danh
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: thu sach y nang mai hoi. hieu van cau truc va hanh vi ((cau tren) OR (cua viet))~.
• Adding a wildcard symbol may retrieve word variants: thu sach y nang mai hoi. hieu van cau truc va hanh vi ((cau tren) or (cua viet))*.