Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
doc sach » hoc sach, toc sach, nuoc sach
thuc van » thuc vat, thuc dan, thuc va
su sach » so sach, vu sach
ve pham » vi pham, ve phan, ve phat
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
v pham » vi pham, d pham
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: ((su sach) or (doc sach)) ky nang ma hoi. hieu ((ve pham) OR (v pham)) thuc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (doc sach)) ky nang ma hoi. hieu ((ve pham) OR (v pham)) thuc van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (doc sach)) ky nang ma hoi. hieu ((ve pham) OR (v pham)) thuc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (doc sach)) ky nang ma hoi. hieu ((ve pham) OR (v pham)) thuc van hanh vi cua tre*.