The origin of atmospheric sulfuric acid from specific natural (such as volcanic emissions and oxidation of biogenic sulfur gases) and anthropogenic (such as sulfur dioxide from fossil fuel combustion) sources is a fundamental, well-established fact of atmospheric chemistry requiring no citation.
The claim states that atmospheric sulphuric acid originates from specific natural and anthropogenic sources. This is a basic, textbook premise of atmospheric science (involving sulfur dioxide oxidation from anthropogenic combustion and natural sources like volcanoes or marine dimethyl sulfide). Therefore, it falls under common knowledge and does not require empirical paper receipts to validate.