Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
hai cua » thai cua, dai cua, hoi cua
vai cua » dai cua, lai cua, bai cua
nang xa » nang x, lang xa, nang ma
y nang » ky nang, ly nang, v nang
va cao » va cac, va dao, va bao
va co » vo co

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 y nang xa hoi. hieu ((va cao) OR (va co)) thuc van hanh ((vai cua) or (hai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang xa hoi. hieu ((va cao) OR (va co)) thuc van hanh ((vai cua) OR (hai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang xa hoi. hieu ((va cao) OR (va co)) thuc van hanh ((vai cua) or (hai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang xa hoi. hieu ((va cao) OR (va co)) thuc van hanh ((vai cua) or (hai cua)) tre*.