Answer:
For gathering experimental results related to a new compound's molecular mass, a primary scientific journal article published by experts in the field of chemistry would likely provide the most accurate and detailed data. This type of publication typically goes through a rigorous peer review process before being accepted for publication, ensuring that the methods used to determine the molecular mass meet high standards of accuracy and reliability. Additionally, this source provides specific details regarding the methodology employed, enabling readers to critically assess the validity of the reported experimental outcomes. Other sources may also provide valuable information but should be cross-checked against multiple reputable sources to ensure accuracy.