Perhaps you should try some spelling variations:
khanh thich » hanh thich, khanh trach, khanh thanh
van khanh » van thanh, van hanh, van anh
thich so » tich so, thich hop, thich sai
don gian » dan gian
hoc giao » hoc cao
tu manh » tu minh, tu hanh, vu manh
tinh so » tinh son, tinh soc, tich so

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (( van khanh thich so - don gian ) OR ( tu manh ((tinh so) OR (dinh so)) - hoc giao ))~.
• Adding a wildcard symbol may retrieve word variants: (( van khanh thich so - don gian ) or ( tu manh ((tinh so) or (dinh so)) - hoc giao ))*.