Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
cua tre » cuu tre, cua triet, dua tren
duc van » duc va, duc tan, duc manh
cam duc » cam xuc, cao duc, pham duc
hieu ve » hieu va, hieu van
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
ve cam » ve cham, ve cac, va cam
cua te » cua tu

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

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