Perhaps you should try some spelling variations:
toc sach » thuoc sach, nuoc sach, toc san
doc sach » nuoc sach, dac sac, bo sach
hoc sach » hoc sinh, hoc cac, hoc anh
vai cuu » vai cua
dan vai » dan va, dan tai, dan vat
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
cuu tre » cua tre, cau tren, cau treo
va nam » van nam, ha nam, va nay
nam tu » nam thu, nam thuc
va dan » ca dan, va dao, va dau

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))) or (hoc sach)) ky lang xa hoi. hieu va nam tu va dan vai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((toc sach) OR (doc sach))) OR (hoc sach)) ky lang xa hoi. hieu va nam tu va dan vai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((toc sach) OR (doc sach))) or (hoc sach)) ky lang xa hoi. hieu va nam tu va dan vai cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((((toc sach) OR (doc sach))) or (hoc sach)) ky lang xa hoi. hieu va nam tu va dan vai cuu tre*.