Comparison of the professional skills of the Moon, Yuan tengfei, and Yan chongnian, as well as some of the learning methods and principles of books

I have heard of part of the story "What is history?" by Yuan tengfei. But I didn't pay attention to it any more. Until recently I heard that he was blocked, I found out his lecture record and listened to it.
When Yan chongnian talked about the history of the Ming Dynasty several years ago, he watched TV and didn't watch it all. However, I found the audio file, which is basically complete.

My feeling for the three people in history is as follows:
1: Yan chongnian is a serious historian with the highest level. Of course, he worships the first six emperors of the Qing Dynasty, which is controversial. When I look at historical figures, he is also an ordinary person, not an expert. It is said that many experts studying historical figures worship their research objects. In addition to Yan chongnian, The February river written by emperor Yong Zheng is also an example.
2: Yuan tengfei is an ordinary historical teacher. After graduation, I don't seem to be very concerned with the latest academic achievements in history. But at least understand the basic academic views.
3: the bright moon of the year is quite special. It is basically self-taught. The special case is not that he learns by himself, but that he is able to make things at last. This person's point of view may be to look at the history directly to see first-hand materials, and also seem to despise the historian. In my opinion, this learning is very laborious.

I think that when learning new knowledge, we should first develop towards Yuan tengfei, try to understand the overall situation and be familiar with the basic situation, after learning, you can develop towards Yan chongnian and become an expert in a certain aspect. The method of Bright Moon in that year is not advisable. He directly contacts details. It is very likely that there are problems in the general direction, and it is likely that it takes a lot of effort to understand the overall situation.

Therefore, I think of some simple methods to determine the quality of books: I can refer to the author's self-introduction to see the level of professionalism involved in the book. Taking Health Care books as an example, many low-quality books do not introduce the author, and it can be concluded that they are written by people who are not getting started. Some books blow the author for a long time, but it can be seen that the author is not very professional about the content. Taking the series "seeking medical treatment is better than seeking oneself" as an example, the author LIBA blew himself up for a long time. What are the secrets of the disciples. However, he wrote a medical book. He was neither a doctor nor a medical-related scientific researcher, and did not dare to write his education. Such a book must be of no entry level. Qu Limin's book is more deceptive. It is really an expert to read the introduction. It indicates that the author knows at least how to write the introduction.