Sources are the historian’s raw materials. The remains that the past leaves behind for posterity to examine are called sources. Important Points The historical sources can be of two types– Primary and Secondary. Primary Source- In the study of history as an academic discipline, a primary source is an artifact, document, diary, manuscript, autobiography, recording, or any other source of information that was created at the time under study. It serves as an original source of information about the topic. Historians consider primary sources to be material written by the subject (if a person) or material that was written about a subject by someone who was alive during the time period. Manuscripts that are sources for classical texts can be copies of documents or fragments of copies of documents. ​Secondary Source- Secondary sources analyze a scholarly question and often use primary sources as evidence. It include books and articles about a topic. They may include lists of sources, i.e. bibliographies, that may lead you to other primary or secondary sources. So, correct answer is Collection of daily weather records, Review of Economic Survey of India because they are secondary sources.