where will I get previous year papers of statistical assistant n assistant audit officer's exam? Suggest me good books also for preparation.

Books on Mental Ability
Ramesh Mental Ability Test by Manoj Kr. Singh
Books on General Economics
S.Chand CPT General Economics by S.K. Agarwal
Bharats General Economics for CPT with Multiple Choice Questions by K K Agarwal
Books on Mathematics
Arihant Higher Algebra Hall & Knight by H. S. Hall S. R. Knight
S.Chand Numerical Methods in Science and Engineering by S.Rajasekaran
Books on Statistics
Vikas Mathematics and Statistics for Economics by G.S.Monga
Bharat Quantitative Aptitude For CPT (Mathematics & Statistics) by M.K. Agrawal
S.Chand Practical Statistics by by R.S.N.Pillai & V. Bhagwathi
Books on Computer Science
Galgotia Computer Science Question Bank by S. Jaiswal
Fundamentals of Computer Algorithms by Horowitz Ellis