Perhaps you should try some spelling variations:
nghien huu » nghien cuu, nhiem huu, chien huu
nguyen huu » nguyen duc
hoc khanh » hoc nhanh, hoc thanh, hoc hanh
mach hoc » cach hoc, dich hoc, anh hoc
tu mach » tu cach, tu manh, tu hach
mot hoc » mon hoc, mo hoc, mot goc
va phan » van phan, va phat, va phap
phan va » phan van, nhan va, han va
phong » thong

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu mach hoc tap, ((nghien huu) OR (nguyen huu)) mot hoc khanh phong (tuc or thuc) xa hoi va phan va~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu mach hoc tap, ((nghien huu) OR (nguyen huu)) mot hoc khanh phong (tuc OR thuc) xa hoi va phan va.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu mach hoc tap, ((nghien huu) OR (nguyen huu)) mot hoc khanh phong (tuc or thuc) xa hoi va phan va".
• Adding a wildcard symbol may retrieve word variants: tu mach hoc tap, ((nghien huu) OR (nguyen huu)) mot hoc khanh phong (tuc or thuc) xa hoi va phan va*.