acidic paper v.29:no.141/142(1972:jun./jul.)-v.45:no.209(1990:oct./dic.) acidic paper pH pen test stained pages v.30:no.147(1975:abr./jun.)-v.30:no.148(1975:jul./sept.) warped/cockled v.29:no.145(1972:oct.),v.30:no.147(1975:abr./jun.)-v.30:no.149(1975:oct./dic.)