coal rank distrib ution
high sulphur occurring low rank coal
mining in slices according to coal rank
reserve estimation according to coal rank
Poisson-Poisson distribution Poisson-Binomial distribution Compound distribution
Poisson—Poisson分布Poisson－二项分布复合分布
coal and coal gas opening together
coal and coal industry of Shanxi
coal and coal processing in Shanxi
coal bed methane and coal coordinative development
coal bed methane in coal mine area