| Ubels, Virginia; Yapélé, Jean-Pierre | Boro kè Bɔ̌kɔ: Mbete fírma fè kè nzák karang 6 | 1985 | | |
| Ubels, Virginia; Yapélé, Jean-Pierre | Gama kè Kudu: Mbete fírma fè kè nzák karang 3 | 1985 | | |
| Ngang, David; Ubels, Virginia; Ulfers, Robert; Yapélé, Jean-Pierre | Mbete firma fe ke nzak karaŋ 5 (Syllabaire volume 5 en langue karang) | 2001 | | |
| Ubels, Virginia; Yapélé, Jean-Pierre | Mbete firma fe ke nzak karaŋ 3 | 1998 | | |
| Ubels, Virginia; Yapélé, Jean-Pierre | Bɔ̌kɔ kè Kuɗu: Mbete fírma fè kè nzák karang 5 | 1985 | | |
| Ngang, David; Ubels, Virginia; Ulfers, Robert; Yapélé, Jean-Pierre | Mbete firma fe ke nzak karaŋ 6 (Syllabaire volume 6 en langue karang) | 2001 | | |
| Ubels, Virginia; Yapélé, Jean-Pierre | Mbete firma fe ke nzak karaŋ 4 | 1998 | | |
| Ubels, Virginia; Yapélé, Jean-Pierre | Yóro kè Dìla: Mbete fírma fè kè nzák karang 4 | 1985 | | |
| Ubels, Virginia | Mbete fírma fè kè nzák karaŋ 2 | 1984 | | |
