tuned bib;

--- a/src/Doc/manual.bib	Sat Mar 21 15:47:45 2020 +0100
+++ b/src/Doc/manual.bib	Sat Mar 21 15:51:05 2020 +0100
@@ -2204,8 +2204,8 @@
   booktitle = {Intelligent Computer Mathematics (CICM 2019)},
   year = {2019},
   editor = {Cezary Kaliszyk and Edwin Brady and Andrea Kohlhase and Sacerdoti Coen, Claudio},
-  volume = {????},
-  series = LNAI,
+  volume = {11617},
+  series = "LNAI",
   publisher = {Springer},
   note = {\url{https://arxiv.org/abs/1905.01735}}
 }