Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
thuc dan » thuc hanh, hoc dan, thuc vat
chu tre » cho tre, cuu tre, cau tren
dan dan » dang dan, ban dan, dao dan
hieu va » lieu va, hieu qua
chu tri » chua tri, chu thi, chu tai
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
dan va » doan va, dan ca, ban va
va am » va lam, va cam

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