Update README.md

Author: metazip

README.md

@@ -20,6 +20,9 @@ a functional style and its algebra of programs"**, [Backus-Turing-Award-Lecture]
 - MacLennan/Functional Programming: Practice and Theory, [borrow eBook](https://archive.org/details/functionalprogra0000macl), Page 221ff: Higher-Order Functions
 - Instance variables, a [way out](https://esolangs.org/wiki/FP_trivia) of the variable abstinence --> "Why didn't the ALGOL Committee" in EWD692
 - Dijkstra EWD692: [A review of the 1977 Turing Award Lecture by John Backus](https://www.cs.utexas.edu/users/EWD/transcriptions/EWD06xx/EWD692.html)
+- [FP](http://www.math.bas.bg/~bantchev/place/fp.html) (english)
+- [Introduction to FL and PLaSM](https://media.johnwiley.com.au/product_data/excerpt/29/04718994/0471899429.pdf)
+- [The FL Project: Design of a Functional Language](Introduction to FL and PLaSM (PDF; 2,5 MB))
 
 ### Last Years of John Backus
 Oral History of John Backus