Perhaps you should try some spelling variations:
thuat mach » thuat sach, thuat tach, thuyet mach
tri thuat » trien thuat, ki thuat, tri thuc
pho thong » he thong
sach tren » sach tien, sach tranh
hanh khoa » hang khoa, anh khoa, hanh hoa
sach tri » sach tai, sach truc, sach bai
mach hoc » cach hoc, dich hoc, anh hoc
tren tuc » tren thuc, trong tuc, tren thi
tuc hanh » thuc hanh, tuc thanh, duc hanh
khoa hoc » hoa hoc
tu sach » thu sach, su sach, te sach
vu sach » vu bach, su sach, vu khach
thuong » truong, huong, phuong

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 tri thuat mach hoc pho thong ) or ( vu sach tren tuc hanh khoa hoc thuong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tri thuat mach hoc pho thong ) OR ( vu sach tren tuc hanh khoa hoc thuong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach tri thuat mach hoc pho thong ) or ( vu sach tren tuc hanh khoa hoc thuong ))*.