Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, va tinh
van hanh » van thanh, ban hanh, van anh
te sach » toc sach
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
qua cho » qua co, qua kho, qua chu
cua tre » cua te, cuu tre, cua triet
cho xu » chao xu, choi xu, cho xa
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((ky lang) OR (ky dang)) hoa hoc. hieu qua cho xu ((va thanh) or (van hanh)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ky lang) OR (ky dang)) hoa hoc. hieu qua cho xu ((va thanh) OR (van hanh)) di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ky lang) OR (ky dang)) hoa hoc. hieu qua cho xu ((va thanh) or (van hanh)) di cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ((ky lang) OR (ky dang)) hoa hoc. hieu qua cho xu ((va thanh) or (van hanh)) di cua tre*.