Perhaps you should try some spelling variations:
khanh tich » thanh tich, khanh trach, phan tich
manh tinh » man tinh, manh binh, canh tinh
vu khanh » vu thanh, van khanh, duy khanh
don gian » dan gian
tich so » tich bao, tinh son
tu manh » tu minh, tu hanh, vu manh
tinh so » tinh son, tinh soc, dinh so

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( vu khanh tich so - don gian ) or ( tu manh tinh so - hoc cao ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( vu khanh tich so - don gian ) OR ( tu manh tinh so - hoc cao ))*.