Perhaps you should try some spelling variations:
dang thai » dang thi, dang hai, dang khai
hoc sach » hoc sinh, hoc cac, hoc anh
thai cua » than cua, tai cuc, tri cua
sach ky » sac ky, sach y, sach ty
van bac » van ban, van bao, van bau
dan bac » dan ba, dong bac, gian bac
van hac » van hoc, van ha, van hai
va dang » van dang, va nang, va lang
cua tre » cua te, cuu tre, cua triet

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 nang x ho. thi ((((van bac) OR (dan bac))) or (van hac)) nuoc va dang thai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky nang x ho. thi ((((van bac) OR (dan bac))) OR (van hac)) nuoc va dang thai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ky nang x ho. thi ((((van bac) OR (dan bac))) or (van hac)) nuoc va dang thai cua tre".
• Adding a wildcard symbol may retrieve word variants: hoc sach ky nang x ho. thi ((((van bac) OR (dan bac))) or (van hac)) nuoc va dang thai cua tre*.