1. Extrinsic evidence includes scholarly journal articles and expert testimony.2. This other evidence is known as extrinsic evidence and is a fairly common principle. 3. Extrinsic evidence is held to be of equal value to evidence from another source.4. This is known as extrinsic evidence . 5. In its summary the commission wrote : " Independent of extrinsic evidence , the Commission finds: 6. Extrinsic evidence is evidence about the interpretation of a written contract that is not contained in the contract.7. Extrinsic evidence is defined as evidence outside the writings, in this case evidence outside of the deed.8. Extrinsic evidence is testimony, expert opinion, or other unwritten sources; extrinsic evidence may not contradict intrinsic evidence.9. Extrinsic evidence is testimony, expert opinion, or other unwritten sources; extrinsic evidence may not contradict intrinsic evidence. 10. By the flexible approach, extrinsic evidence may be admitted in the determination of whether the agreement is wholly in writing.