Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hanh vai » hanh vi, hanh va, hanh tai
nang dau » hang dau, xang dau, nang du
cam tuc » cam xuc, cam tu, nam thuc
cuu tre » cua tre, cau treo
va hanh » van hanh, va thanh, va danh
sach ty » sach tu, sach thu, xach tay
hieu va » lieu va, hieu qua
dau hoi » cau hoi, dai hoi, dan hoi
tuc va » thuc va, truc va, tuc xa
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ty) or (sach y)) nang dau hoi. hieu va cam tuc va hanh vai ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach y)) nang dau hoi. hieu va cam tuc va hanh vai ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (sach y)) nang dau hoi. hieu va cam tuc va hanh vai ((cuu tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach y)) nang dau hoi. hieu va cam tuc va hanh vai ((cuu tre) OR (cau tren))*.