Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
danh vai » danh sai, danh va, doanh van
va cham » va chat, va tham
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, va hanh
cua tre » cua te, cuu tre, cua triet
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
xuc va » duc va, tuc va, luc va
va cam » va cac, va cao, va cai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (doc sach)) ky lang xa hoi. hieu ((va cam) OR (va cham)) xuc va danh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ky lang xa hoi. hieu ((va cam) OR (va cham)) xuc va danh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) ky lang xa hoi. hieu ((va cam) OR (va cham)) xuc va danh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) ky lang xa hoi. hieu ((va cam) OR (va cham)) xuc va danh vai cua tre*.