Question: What type of pistol are the Astra A-60 and Walther PP?

Context paragraphs:
9×18mm Ultra: It was originally developed in the 1936 for use by the Luftwaffe, but was not adopted at that time.  In the 1972-1973 time frame, Walther introduced the Walther PP Super chambered in the cartridge for the West German Police.  The Walther PP Super was discontinued in 1979.  The cartridge was made available to the civilian market in 1975.

Walther PP: The Walther PP ("Polizeipistole", or police pistol) series pistols are blowback-operated semi-automatic pistols, developed by the German arms manufacturer Walther.

Walther GSP: The Walther GSP, "Gebrauchs Sportpistole" (Sport Pistol for Standard Use), is a single-action, precision targetshooting pistol made in Germany by Walther Sportwaffen.  It has the same technical base as the Walther OSP and thus is almost identical in outward appearance, albeit slightly longer and heavier than the OSP.

Walther PPS: The Walther PPS ("Polizei-Pistole Schmal" / Police Pistol Slim) is a semi-automatic pistol developed by the German company Carl Walther GmbH Sportwaffen of Ulm for concealed carry for civilians and plainclothes law enforcement personnel.  It is available in either 9×19mm Parabellum or .40 S&W chamberings.  It was first shown in 2007 at the IWA & OutdoorClassics and is a slim polymer framed weapon of similar size to the Walther PPK pistol.  The PPS is however technically much more based on the Walther P99 pistol.

Walther PPQ: The Walther PPQ ("PolizeiPistole Quick Defence" / Police Pistol Quick Defense) is a semi-automatic pistol developed by the German company Carl Walther GmbH Sportwaffen of Ulm for law enforcement, security forces and the civilian shooting market as a potential replacement for the Walther P99.  It is available in .22 Long Rifle, 9×19mm Parabellum, 9×21mm, .40 S&W, and .45 ACP chamberings.

Walther SSP: The Walther SSP is a precision target shooting pistol made in Germany by Walther Sportwaffen.  The SSP was created in response to ISSF rule changes to the 25 m Rapid Fire Pistol in 2005 which effectively rendered the Walther OSP obsolete.  The new rules precluded use of the .22 Short cartridge as well as wrap-around grips and light trigger pulls (pressure required to pull/activate trigger).

Astra A-60: The Astra A-60 is a double-action,single-action, semi-automatic pistol at one time produced in Spain by Astra-Unceta y Cia SA.  The design is similar to the Walther PP and features a slide-lock release lever.

Walther Model 9: The Walther Model 9 was a striker fired semi-automatic pistol produced by Walther arms and chambered in .25 ACP.  The decision to use a striker vs. that of an internal hammer like on the Walther Model 8 was to reduce overall size of the gun, but sacrificed reliability.  If the striker spring is compressed for extended periods of time it can weaken and not have enough force to ignite the primer causing a miss-fire.  This can be avoided by not keeping the pistol cocked when not in use.  It has a 6 round detachable box magazine.  The Model 9 is similar in size and function to the Baby Browning pistol which is only slightly larger.  The Browning is also chambered in the .25 ACP cartridge.

Type 64 pistol: The Type 64 pistol () is a semi-automatic pistol, formerly in service with the People's Liberation Army (PLA) but has since been replaced by several other firearms, although it still remains in service with some Chinese police forces.  The Type 64 pistol was the first firearm to be indigenously developed by the People's Republic of China and was first only issued to high-ranking military officers and officials, but has since been distributed throughout the PLA.  The Type 64 pistol has subsequently been distributed to various People's Armed Police and civilian police forces.  The Type 64 pistol should not be confused with the unrelated, but similarly named, Type 64 silent pistol () which can be distinguished from the Type 64 pistol, by its large, integral suppressor.

Walther Olympia: The Walther Model 1936 Olympia II is a single action semi-automatic handgun manufactured by Walther.  The first version was the M1925, formally known as the Automatic Walther Sport Pistol cal.22 LR, and was introduced in 1925.  It was followed by the M1932, the Olympia Pistole I, and used to good effect in the 1932 Olympic Games.  The final development Walther made was the M1936 Olympia II that won five Gold Medals at the 1936 Berlin Olympics and effectively ended the Olympic reign of the Colt Woodsman Target model.  The pistol continued to be manufactured up until 1944, but no major changes were made during the war.  In 1952 the pistol was reintroduced under license by Hämmerli-Walther.  In 1957 Smith & Wesson introduced the Model 41, based on the Olympia-Pistole.  The Norinco TT Olympia is a Chinese copy of the Walther M1936 Hunter made sometime after 1980.

Supporting paragraphs: Astra A-60 Walther PP
Answer: semi-automatic pistols