or Prelims:
Ancient + Medieval: Old NCERTs + Mock tests to cover gaps.
Modern History: Undoubtedly Modern Indian History Spectrum by Rajiv Ahir(No other source to be even Looked at)
For Mains:
Refer Previous Years Questions. UPSC is obsessed With Gandhi, At least I am not gonna read Bipin Chandra, I would say take your call. I would Rather re-read the same sources along with solving questions in Test series. If the Pattern is to be Followed 1–2 ques on Art and Culture and 1–2 Questions from Modern specially Role of Gandhi and Role Of Women In India’s Freedom Struggle. You can also refer NCERT Fine Arts for Art and Culture related Questions.
Edit-1 Thanks Man for letting me know I had messed up the answer and Thats really bad for me to have done 70 days prior to PT. But I take it as a lesson. So addressing your query for World History:
I would recommend VISION IAS material and Vajiram Class Notes(As I had taken coaching so I feel its fine to read) plus Previous Years Questions. Read each and every Word of Syllabus and be prepared with 7–10 points each.In syllabus its mentioned Vaguely Colonialism and Decolonialism. In 2016 Decolonisation of Africa was asked(as in 2015 India-Africa Summit took place) and this Time in 2017 Decolonisation of Malay Peninsula was asked for reasons best known to UPSC. So whatever the case be, Have a standardised Pattern to answer any such Question like Political,Economic and Social Reasons for the Decolonisation and how the process took about to shape the current Events happening. Try to link History with Current after all its all about providing as many perspectives as possible.
Previous trends to be followed at max 1–2 questions which are too General to mentioned in any Standard book. Again take your call. I don’t prefer to read a whole new book like Norman Lowe or Lucent but again its your call. I would watch videos on Mrunal or read their Matter to compliment Material of Vision Ias along with Previous Years Questions.Thanks.
Be smart than Emotional.
