Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
hieu van » hieu va, thien van, lieu va
tay tang » tay lang, tay trung, tay quang
danh va » doanh va, hanh va, anh va
va danh » va dinh, va dan, va hanh
nam xua » nam cua, nam mua, nam qua
cua tre » cua te, cuu tre, cua triet
xua va » xuat va, vua va, sua va
y lang » o lang, _ lang, tay lang
va cua » va chua, via cua, ca cua

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 (hoc sach)) ((y lang) or (tay tang)) xa hoi. hieu van nam xua va danh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ((y lang) OR (tay tang)) xa hoi. hieu van nam xua va danh va cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (hoc sach)) ((y lang) or (tay tang)) xa hoi. hieu van nam xua va danh va cua tre*".