Perhaps you should try some spelling variations:
thanh cac » thanh bac, thanh ca, tranh cac
hieu van » hieu va, thien van, lieu va
hanh cac » hang cac, hanh cat, nhanh cay
so sach » so sanh, bo sach, co sach
cam tuc » cam xuc, cam tu, nam thuc
sach ky » sac ky, sach y, sach ty
van cam » van nam, van lam, van cau
tang ma » mang may, tang van
sang ma » nang ma, sang tao, mang may
cua tre » cua te, cuu tre, cua triet
tuc va » thuc va, truc va, tuc xa

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky ((sang ma) or (tang ma)) hoi. hieu van cam tuc va ((thanh cac) OR (hanh cac)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky ((sang ma) OR (tang ma)) hoi. hieu van cam tuc va ((thanh cac) OR (hanh cac)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky ((sang ma) or (tang ma)) hoi. hieu van cam tuc va ((thanh cac) OR (hanh cac)) cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ky ((sang ma) or (tang ma)) hoi. hieu van cam tuc va ((thanh cac) OR (hanh cac)) cua tre*.