Perhaps you should try some spelling variations:
doc sach » toc sach, nuoc sach, dac sac
hoc sach » hoc sinh, hoc cac, hoc anh
danh vai » danh sai, danh va, doanh van
dau duoc » da duoc, dat duoc, dau nuoc
lang van » dang van, tang van, hoang van
hieu van » hieu va, thien van, lieu va
vai cua » dai cua, hai cua, lai cua
ma danh » va danh, ma dan, mo danh
duoc ma » duoc lam
van dau » van dao, phan dau
lang xa » lang ha, dang xay
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: ((doc sach) or (hoc sach)) ky ((lang xa) or (lang van)) hoi. hieu van dau duoc ma danh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (hoc sach)) ky ((lang xa) OR (lang van)) hoi. hieu van dau duoc ma danh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((doc sach) or (hoc sach)) ky ((lang xa) or (lang van)) hoi. hieu van dau duoc ma danh vai cua tre*.