Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
phan dau » phan tu, hang dau
sach ty » sach y, sach tu, sach thu
duc van » duc va, duc tan, duc manh
tu sach » thu sach, su sach, te sach
ty nang » ky nang, ty xang, ty hang
cuu tre » cua tre, cau tren, cau treo
ve cac » va cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty nang x ho. hieu ((ve cac) OR (vien cac)) duc van ((thanh san) or (phan dau)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang x ho. hieu ((ve cac) OR (vien cac)) duc van ((thanh san) OR (phan dau)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang x ho. hieu ((ve cac) OR (vien cac)) duc van ((thanh san) or (phan dau)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang x ho. hieu ((ve cac) OR (vien cac)) duc van ((thanh san) or (phan dau)) cuu tre*.