Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
van hanh » van thanh, ban hanh, van anh
dang mam » dang nam, dang mau, dang mat
xuc van » duc van, luc van, vuc van
vu cham » va cham, vu kham, tu cham
sach ky » sac ky, sach y, sach ty
dang ma » dang mau, dang mat, tang ma
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ky ((dang ma) or (dang mam)) hoi. hieu ((ve cam) or (vu cham)) xuc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky ((dang ma) OR (dang mam)) hoi. hieu ((ve cam) OR (vu cham)) xuc van hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: hoc sach ky ((dang ma) or (dang mam)) hoi. hieu ((ve cam) or (vu cham)) xuc van hanh vi cua tre*.