This book is a very quick overview of what was known at the time (1989) about the connection between quantum field theory and knot theory. The subject of topological quantum field theories and their connection with knot invariants was at that time just beginning thanks to the work of Edward Witten on the Jones polynomial.
The approach that the author takes in the book is very formal and not for the beginner who is looking to learn about these results. Readers with enough background to read it will no doubt want to read more up-to-date treatments of the subject. The book however does give an indication of how Feynman path integrals are used to define the invariants. The use of these is not rigorous mathematics and this has not changed at the present day.