I have the same Meeus book. It's been a while since I read it, but my impression was the signs of longitudes being turned around was not unique to his book, but was rather a convention throughout astronomy, so you could expect to find whatever other books you're recommended would have the same convention.
When I was contemplating my own implementation from that book my sketchy API design just included a mandatory extra parameter to accompany such numbers, which would explicitly indicate whether the astronomical or other sign convention was to be used.
Thanks for the hints. I ordered two promising books in German language:
"Astronomie" by Pearson and "Astronomie in Theorie und Praxis" (3 volumes) by Erik Wischnewski. Thats some 2000 pages of stuff to read, so let's see where this takes me.
I would also like to add my interest for this same topic.
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The topic of the currency of Meeus's book came up on stack exchange [1]. The consensus seems to be that there's no replacement yet, but that there are some better ephemerides available - but figuring out how to use those rather than the ones in the book is difficult for someone not familiar with this stuff (like me).
[1] https://astronomy.stackexchange.com/questions/53967/modern-e...