Perhaps you should try some spelling variations:
thuoc sach » nuoc sach, thuat sach, thuoc sinh
van hanh » van thanh, ban hanh, van anh
hoc sach » hoc sinh, hoc cac, hoc anh
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
xuc van » duc van, luc van, vuc van
van cam » van nam, van lam, van cau
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
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: ((su sach) or (((thuoc sach) OR (hoc sach)))) ky sang ma hoi. hieu van cam xuc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (((thuoc sach) OR (hoc sach)))) ky sang ma hoi. hieu van cam xuc van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (((thuoc sach) OR (hoc sach)))) ky sang ma hoi. hieu van cam xuc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (((thuoc sach) OR (hoc sach)))) ky sang ma hoi. hieu van cam xuc van hanh vi cua tre*.