TY  - SER
AU  - Scott,Dan
TI  - A bit of history: Overcoming early setbacks, PDC bits now drill 90%-plus of worldwide footage
PY  - 2015///
CY  - 
PB  - 
N1  - Decades after invention of polycrystalline diamond cutters, PDC bits edge out roller cones with advances in cutters, stability, hydraulics
ER  -