Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thuc van » thuc vat, thuc dan, thuc va
van hanh » van thanh, ban hanh, van anh
vu sach » vu bach, su sach, vu khach
nang xa » nang x, lang xa, nang ma
ve pham » vi pham, v pham, ve phat
ve phan » va phan, ke phan, ve phat
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((vu sach) or (toc sach)) ky nang xa hoi. hieu ((ve pham) OR (ve phan)) thuc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu sach) OR (toc sach)) ky nang xa hoi. hieu ((ve pham) OR (ve phan)) thuc van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu sach) or (toc sach)) ky nang xa hoi. hieu ((ve pham) OR (ve phan)) thuc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((vu sach) or (toc sach)) ky nang xa hoi. hieu ((ve pham) OR (ve phan)) thuc van hanh vi cua tre*.