Perhaps you should try some spelling variations:
sach tham » sach nha
va trien » va truyen, va thiet, va tuyen
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
dinh vu » dich vu, dinh ve, dinh cu
va dinh » van dinh, va kinh, va tinh
cam tuc » cam xuc, cam tu, dam thuc
nano o » nano 1, nano cuo, nano mot
o hoc » co hoc, mo hoc, so hoc
vu va » vu van, tu va, su va

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 tham) or (sach thieu)) nano o hoc. hieu van ((cam tuc) OR (nam thuc)) va dinh vu va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach tham) OR (sach thieu)) nano o hoc. hieu van ((cam tuc) OR (nam thuc)) va dinh vu va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach tham) or (sach thieu)) nano o hoc. hieu van ((cam tuc) OR (nam thuc)) va dinh vu va trien".
• Adding a wildcard symbol may retrieve word variants: tu ((sach tham) or (sach thieu)) nano o hoc. hieu van ((cam tuc) OR (nam thuc)) va dinh vu va trien*.