Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
van hanh » van thanh, van anh, van ban
ban hanh » ban hang
ly nang » ky nang, ly hang, ly vang
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
cuc tre » duc tre, cua tre, cuu tre
ve dat » de dat, va dat, ve dao

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)) ly nang ma hoa. hieu ve dat nuoc ((van hanh) or (ban hanh)) tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ly nang ma hoa. hieu ve dat nuoc ((van hanh) OR (ban hanh)) tai cuc tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) ly nang ma hoa. hieu ve dat nuoc ((van hanh) or (ban hanh)) tai cuc tre*.