Hey as per my idea there are various books available for SSC Combined Graduate Level Exam and here I am giving you its details

Nationality
Candidate should be Indian

Age limit
Candidate should be between 20 to 27

Age relaxation
SC/ ST 5 years
OBC 3 years
PH 10 years
PH + OBC 13 years
PH + SC/ST 15 years

Qualification
Candidate should be graduate from recognised university

Here I am giving you Best Books for SSC Combined Graduate Level Exam

S.S.C. Combined Graduate Level Exam: Tier I & II
Arihant’s Fast Track Objective Arithmetic
Objective General English by S P Bakshi (Arihant)
Analytical Reasoning by M K Pandey
Manorama Yearbook 2016 (English)
Quantitative Aptitude for Competitive Examinations (R S Aggarwal) OR
Arihant’s Fast Track Objective Arithmetic
Magical Book On Quicker Maths