If you are looking for books on results here are my recommendations for anyone looking for pre Motocourse (1976) stats.
As well as the Ron Maggs book there are:
Motorrad Weltmeisterschaft by Volker Rauch. This is a German yearbook that starts in 1968 and is written in german. It is pretty good, like Maggs some of the names and nationalities are not quite right for the early years, but overall it is pretty accurate. Many of the Aussies and Kiwis are listed as British, (possibly due to running under ACU licences?), but it does have a pretty comprehensive results list. I started picking them up a few years ago when they were cheap, but they have risen in price quite a bit recently. They are still being published now I think and are mostly available on German eBay or the Abebooks search website or zvab. It is about A5 size.
L'Annee Motorcycliste is a French Motocourse type book (and written in French), it started in 1969 and the results listing is also good, but it still has some errors too. It only lists points finishers, but does have grid positions from 1975 onwards. There were two English language versions in 76 and 77, entitled Moto Year. They also contain the Motocross and trials results for the year too. It is a big A4 size book, just like Motocourse.
Other have been mentioned in the forum before, but I will put them here for completeness.
Motorcycle Racing guide 1974 by SIL gives the 1973 results in detail, this also has Motocross, Trials and Speedway results for the year too.
Grand Prix Motorcycle Championships of the World 1949 - 1975 by Maurice Bula has listings of all points scoring finishers for all classes up to 1975.
The FIM Grand Prix Guide by Werner Haefliger is similar but only has the 125, 250 and 500 results. I know of 2 versions 1996 and 2005, but I think there are more recent versions available. The 1996 version is listed as the Marlboro guide.
There are also the MCN yearbooks which ran from 1975 through to 1980. These had loads of results from each year for the World and British championships.
I have heard there is a Dutch publication that started results from the late 1960s but I haven't been able to track this one down, probably as my Dutch language skills, to my shame, are non existent.
I hope this is of some use to anyone else interested in results and if I have missed anything please let me know.